NOAA's National Centers for Environmental Information
Issued 14 July 2021
Please note that the values presented in this report are based on preliminary data. They will change when the final data are processed, but will not be replaced on these pages.
National Drought Highlights
- Based on the Palmer Drought Index, severe to extreme drought affected about 36% of the contiguous United States as of the end of June 2021, an increase of about 8% from last month. About 4% of the contiguous U.S. fell in the severely to extremely wet categories.
- About 47% of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of June.
- On a broad scale, the 1980s and 1990s were characterized by unusual wetness with short periods of extensive droughts, the 1930s and 1950s were characterized by prolonged periods of extensive droughts with little wetness, and the first two decades of the 2000s saw extensive drought and extensive wetness (moderate to extreme drought graphic, severe to extreme drought graphic).
- A file containing the national monthly percent area severely dry and wet from 1900 to present is available for the severe to extreme and moderate to extreme categories.
- Historical temperature, precipitation, and Palmer drought data from 1895 to present for climate divisions, states, and regions in the contiguous U.S. are available at the Climate Division: Temperature-Precipitation-Drought Data page. These filenames begin with "climdiv".
- According to the weekly U.S. Drought Monitor (USDM), as of June 29, 2021, 47.19% of the contiguous U.S. (CONUS) (39.53% of the U.S. including Alaska, Hawaii, and Puerto Rico) was classified as experiencing moderate to exceptional (D1-D4) drought.
Detailed Drought Overview
Upper-level troughs and ridges migrated through the atmospheric circulation over the CONUS during June 2021, with ridging dominating. The upper-level troughs dragged surface lows and fronts with them, and these brought rain to parts of the Southwest, southern Plains to Southeast, Midwest, and a few coastal areas of Oregon and Washington. These areas were wetter than normal for the month. But much of the West, central to northern Plains, and Northeast was drier than normal under the frequent ridging. Cooler Canadian air behind the cool fronts lingered at times in the southern Plains to Southeast. The cooler air combined with cloudy skies and rain associated with the fronts and remnants of Tropical Storms Claudette and Danny to give these areas monthly temperatures that were near to cooler than normal. The frequent anomalous ridging over the West and northern Plains to Northeast resulted in much warmer-than-normal monthly temperatures for these regions, with record warmth occurring in the West and Northeast.
The below-normal precipitation during June and for the last several months, and early melt of the below-normal winter mountain snowpack in the West, have resulted in low to record-low streamflow, low groundwater (USGS and GRACE satellite observations) levels, and dry soil moisture (SMOS satellite observations; SPoRT satellite-based observations for 0-10 cm [0-4 inches] depth, 0-40 cm [0-16 inches] depth, 0-100 cm [0-39 inches] depth, 0-200 cm [0-79 inches] depth; GRACE satellite-based observations for surface and root zone soil moisture; the USDA Crop Condition and Soil Moisture Analytics [CASMA] soil moisture anomaly for topsoil and subsoil, CASMA soil moisture category for topsoil and subsoil, and field observations of topsoil moisture; the satellite-based Vegetation Condition Index (VCI); the VegDRI and QuickDRI products; and CPC, Leaky Bucket, NLDAS, and VIC models). These conditions were especially notable across the West, northern Plains, Northeast, southern High Plains, and parts of Florida and the Midwest. The month began with several large wildfires occurring in the Southwest and southern Florida; as the month progressed, they expanded in the West and were reduced in Florida (wildfire maps for June 1, 11, 14, 21, 28, 30), with total acreage burned for the year to date of about 1.5 million acres, which is below average.
Reports received through the Condition Monitoring Observer Reports (CMOR) system included continued drought impacts to farming and ranching operations, especially forage and feed issues, plant and animal stress, and lack of water, as well as dry lawns, fire risk, poor air quality, stress to people, and less food and water for wildlife, mostly in the West and northern Plains. The forage shortage was leading to livestock sales in Montana, Wyoming, and the Dakotas, with whole herds being sold in North Dakota. Livestock was also being sold in western Colorado. Reports have also come in to the National Drought Mitigation Center from the Midwest; various cities in Minnesota and Wisconsin were starting to implement water restrictions. Mandatory water restrictions were enacted in New Hampshire while water restrictions continued to tighten in California. Governor Kristi Noem declared a state of emergency in South Dakota to allow haying of roadside grasses. Drought emergencies were also declared in Montana, Oregon, and western Colorado. The heat, drought, and lack of food were forcing more wildlife, notably bears and rattlesnakes, to encroach upon urban areas in California, Nevada, and Utah. Warm water and low streamflows prompted fishing restrictions in Oregon, Colorado, and Montana. Lake Mead fell below 1,071.61 feet above sea level on June 9, hitting the lowest level since the construction of the Hoover Dam in the 1930s. Each day brought new record lows. On June 16, the lake level fell to 1070.6 feet. The falling lake level will result in reduced hydropower production. A Lake Mead water shortage declaration is expected from the federal government in August, which will lead to large cuts in water allocations for Arizona, New Mexico and Mexico. Administration officials expect electricity generation from conventional hydropower sources in the West to decrease by about 11 percent in 2021, compared to 2020. In mid-June, the UVI Caribbean Green Technology Center and the Virgin Islands Department of Agriculture were asking farmers to start lowering water use and to begin conserving as the island remained in drought; farmers were encouraged to explore all types of water conservation, beginning with monitoring for and repairing irrigation line leaks.
As a result of these conditions, drought or abnormal dryness expanded or intensified in the West, Northeast, central to northern Plains and Upper Mississippi Valley, and Hawaii. Beneficial rains caused drought or abnormal dryness to contract or decrease in intensity in the southern High Plains, southern Appalachians to Mid-Atlantic states, and parts of Michigan, Florida, and Puerto Rico. Drought expansion exceeded contraction with the USDM-based national moderate-to-exceptional drought footprint across the CONUS rising from 43.7 percent at the end of May to 47.2 percent at the end of June (from 36.5 percent to 39.5 percent for the 50 States and Puerto Rico). According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 47.4 percent of the CONUS was in moderate to extreme drought at the end of June, an increase compared to the end of May. The percent area of the CONUS in moderate to extreme drought has hovered between 35 and 48 percent for the last ten months (since September 2020).
Drought conditions at the end of June, as depicted on the June 29, 2021 USDM map, included the following core drought and abnormally dry areas:
- Moderate (D1) to extreme (D3) drought extended from the West Coast to Rocky Mountains and into the adjacent southern High Plains, with a large area of exceptional (D4) drought across the Southwest to southern High Plains, and D4 patches in California, Idaho, and Oregon. The percent area of the West experiencing moderate to exceptional drought, according to USDM statistics, increased from 81.8 percent at the end of May to 87.9 percent at the end of June. This value was exceeded in the 21-year USDM record only during the drought which peaked in August and September of 2003. The end-of-June percent area in extreme to exceptional drought (D3-D4) was 52.8 percent, which is USDM record. The percent area of the West (from the Rockies to the West Coast) in moderate to extreme drought (based on the Palmer Drought Index) soared to about 97.4 percent by the end of June 2021. This exceeded the previous record of 94.4 percent that occurred in September 1934.
- Moderate to exceptional drought expanded in parts of the central and northern Plains and contracted in the southern Plains. The moderate to exceptional drought area expanded from 48.0 percent of the central and northern Plains at the end of May to 54.5 percent at the end of June, and shrank from 38.6 percent of the southern Plains at the end of May to 18.8 percent at the end of June.
- In the Midwest, drought expanded from 18.0 percent of the region at the end of May to 30.9 percent at the end of June. Moderate to severe (D2) drought expanded in Minnesota, Iowa, Wisconsin, and northern Illinois; and a pocket of extreme drought developed along the Illinois-Wisconsin border. In Lower Michigan, moderate drought shrank but a new pocket of severe drought developed in the east.
- Moderate drought ballooned from 2.8 percent of the Northeast at the end of May to 20.1 percent at the end of June, with severe drought developing in Maine and adjacent New Hampshire.
- In the Southeast, beneficial rains eliminated severe drought and shrank moderate drought and abnormal dryness, with the drought footprint decreasing from 20.7 percent of the region at the end of May to 1.6 percent at the end of June.
- Moderate and severe drought expanded significantly from just 7.0 percent of Hawaii at the end of May to over half (56.6 percent) of the state at the end of June, with abnormal dryness or drought increasing to 86.1 percent of the state.
- In the Caribbean, moderate drought was cut in half over Puerto Rico, decreasing from 19.7 percent of the territory at the end of May to 8.3 percent at the end of June. In the U.S. Virgin Islands (USVI), severe drought continued in the south on St. Croix while conditions improved in the north to moderate drought on St. John and abnormal dryness on St. Thomas.
- In the U.S.-Affiliated Pacific Islands (USAPI), drought improved to abnormal dryness in the Marshalls at Wotje, and abnormal dryness ended at Kapingamarangi, with the rest of the USAPI free of drought or abnormal dryness.
- Abnormal dryness shrank to cover 14.1 percent of Alaska.
Palmer Drought Index
The Palmer drought indices measure the balance between moisture demand (evapotranspiration driven by temperature) and moisture supply (precipitation). The Palmer Z Index depicts moisture conditions for the current month, while the Palmer Hydrological Drought Index (PHDI) and Palmer Drought Severity Index (PDSI) depict the current month's cumulative moisture conditions integrated over the last several months. While both the PDSI and PHDI indices show long-term moisture conditions, the PDSI depicts meteorological drought while the PHDI depicts hydrological drought. The PDSI map may show less severe and extensive drought (as well as wet spell conditions) in some parts of the country than the PHDI map because the meteorological conditions that produce drought and wet spell conditions are not as long-lasting as the hydrological impacts.
Used together, the Palmer Z Index and PHDI maps show that short-term drought occurred across most of the West and northern Plains to Upper Mississippi Valley and parts of the central Plains and Northeast, expanding or intensifying long-term drought in these areas (PHDI maps for June compared to May). Short-term wet conditions in the Lower Great Lakes contributed to contraction of long-term drought, and in the Gulf Coast states led to expansion or intensification of long-term wet conditions.
Standardized Precipitation Index
The Standardized Precipitation Index (SPI) measures moisture supply. The SPI maps here show the spatial extent of anomalously wet and dry areas at time scales ranging from 1 month to 24 months.
The SPI maps illustrate how moisture conditions have varied considerably through time and space over the last two years. Dry conditions dominate the West at all time scales, with the dryness more widespread at 2-24 months, and more intense in northern sections at 3 months and in the southern sections at 9-24 months. Dry conditions dominate the northern Plains and Upper Mississippi Valley south to Iowa at the 1- to 12-month time scales. Much of the Northeast is afflicted with dry conditions at the 2- to 12-month time scales, with New England dry at all time scales. The southern Appalachians to Mid-Atlantic States are dry at 2 to 3 months, with parts of Florida dry at 2 to 6 months. Parts of the Great Lakes are dry at the 6- to 12-month time scales. Wet conditions dominate much of the Gulf of Mexico coast at all time scales, the Mid-Atlantic states at 9 to 24 months, and the High Plains of eastern New Mexico, eastern Colorado, and western Texas at 1 to 9 months. Wet conditions are evident in parts of the Midwest (Ohio Valley to southern Great Lakes) at the 1- to 2-month time scales, and central Plains to Ohio Valley at 2 to 9 months. An interesting pattern is evident at the 24-month time scale — very dry conditions dominate across the West, while very wet conditions dominate the Great Lakes and from eastern portions of the southern and central Plains to the southern and mid-Atlantic coast.
Standardized Precipitation Evapotranspiration Index
The SPI measures water supply (precipitation), while the SPEI (Standardized Precipitation Evapotranspiration Index) measures the combination of water supply (precipitation) and water demand (evapotranspiration as computed from temperature). Warmer temperatures tend to increase evapotranspiration, which generally makes droughts more intense.
June is the month that begins climatological summer, which is the warmest season of the year (when evapotranspiration reaches its annual maximum). During June 2021, temperatures were well above normal across the western third and northern third of the CONUS, with record warmth occurring in much of the West and parts of the Northeast. The record warmth extended over the last three months. The increased evapotranspiration resulting from the excessive temperatures contributed to more extreme SPEI values (maps for last 1, 2, 3, 6, 9 months) than SPI values (maps for last 1, 2, 3, 6, 9 months), especially over the West, northern Plains, and New England.
The April-June 2021 SPEI for California was record low, far surpassing previous April-June SPEI values in the 1895-2021 record. The April-June 2021 SPI for California was also record low, but just barely, and it was not as extreme as the SPEI value, which illustrates how the excessively hot temperatures exacerbated the drought conditions. The April-June 2021 SPEI for Oregon was the second driest on record, while the April-June 2021 SPI tied for third driest. In Washington state, the April-June 2021 SPEI ranked third driest while the SPI was second driest, illustrating both the excessive nature of the heat and dryness.
Temperatures have been much warmer than normal in the West, and especially the Southwest, for much of the last one to eight years. The excessive evapotranspiration, especially during the warm season, has contributed to more extreme SPEI values than SPI values for much of this period (SPEI maps for the last 12, 24, 36, 48, 60, 72 months) (SPI maps for the last 12, 24, 36, 48, 60, 72 months).
This is especially evident in Arizona, where the SPEI is record dry at the 48- to 72-month time scales while the SPI is not (48-month and 72-month SPI). The 48- and 72-month SPEI charts for Arizona also illustrate the cumulative effects of the year-after-year excessive heat and dryness since 2000 — these charts show that the state is, and has been for a while, in unprecedented and uncharted territory. Both the SPEI and SPI were record low at the 24-month time scale for Utah, at the 12- and 24-month time scales for Arizona (12- and 24-month SPEI) (12- and 24-month SPI), at the 12-month time scale for California (12-month SPEI) (12-month SPI), and at the 24-month time scale for Nevada (24-month SPEI) (24-month SPI).
Regional Discussion
Hawaii
June, May-June, and April-June 2021 were drier than normal across the main Hawaiian Islands, except for some locations on the leeward side of the Big Island. But with a wet March, wetter-than-normal conditions dominated at most locations at the 4- to 6-month time scales. A mixed precipitation anomaly pattern was evident at 9 months, with drier-than-normal conditions widespread from Oahu to Maui and northern parts of the Big Island at 12 months. A mixed precipitation anomaly pattern was seen at 24 months, with a trend towards wetter-than-normal dominating at longer time scales (last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months) (climate engine model percent of normal precipitation map for the last month). Monthly streamflow was below normal at most gauges across Oahu to the Big Island. Moderate to severe drought spread across parts to most of Oahu to the Big Island, growing from 7.0 percent of the state at the end of May to half (56.6 percent) of the state on the June 29th USDM map.
Alaska
June and May-June were drier than normal from the Bristol Bay and Cook Inlet areas northeast into the interior. This anomaly pattern generally held at the 3-month time scale but became mixed at 4 months, with dryness centering in Cook Inlet by 6 months. Drier-than-normal conditions were evident from the central interior to north slope areas at 9 months with a mixed pattern south to Cook Inlet and some dryness along the Aleutian Chain. At the 12-month time scale, a drier-than-normal pattern was seen across the north, west, Aleutians, and Cook Inlet areas. Wetter-than-normal conditions became dominant at longer time scales (low elevation station precipitation anomaly maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months) (high elevation SNOTEL station precipitation percentile map for the last 1, 3, 9, and 12 months) (high elevation SNOTEL station precipitation anomaly maps for the last 1 and 9 months) (SNOTEL basin precipitation anomaly maps for the last 1, 3, 9, and 12 months) (climate division precipitation rank maps for the last 1, 3, 6, and 12 months) (climate engine model percent of normal precipitation map for the last month) (modeled percent of normal maps from ACCAP for the last month) (Leaky Bucket model precipitation percentile map). June was near to warmer than normal across most of the state. Colder-than-normal temperatures spread from the interior at 3 months to dominate the state by the 6-month time scale, except for warmer-than-normal conditions that continued in the Aleutians. Warmer-than-normal temperatures began encroaching from the west by the 12-month time scale (low elevation station temperature anomaly maps for the last 1, 2, 3, 4, 6, 9, 12 months) (climate division temperature rank maps for the last 1, 3, 6, 12 months) (Leaky Bucket model temperature percentile map). Modeled soil moisture and experimental satellite-based observations of soil moisture (SMOS and SPoRT percentiles for 0-10 cm [0-4 inches] depth, 0-40 cm [0-16 inches] depth, 0-100 cm [0-39 inches] depth, 0-200 cm [0-79 inches] depth) showed drier than normal conditions in parts of the northeast, west central, and south coastal areas. Monthly streamflow (for those streams that were not frozen) was mostly near normal with some above-normal streamflows in the panhandle. A few large wildfires developed in the northwest and central regions by the end of the month (wildfire maps for June 1, 28, 30). According to the National Interagency Fire Center's (NIFC) National Interagency Coordination Center, as of June 30th, 71,961 acres have been burned in Alaska so far this year. Abnormal dryness shrank to cover 14.1 percent of the state on the June 29th USDM map.
Puerto Rico and U.S. Virgin Islands
June 2021 was wetter than normal across most of Puerto Rico (PR) and the northern U.S. Virgin Islands (USVI), with the southern USVI (St. Croix) drier than normal. Drier-than-normal conditions were evident along the southern PR coast and some areas to the north, and continued in St. Croix, at the 2- to 4-month time scales, and spread to the northern USVI by 6 months. By 9 months, the dryness shifted to the northwest coast of PR and continued in the USVI. Drier-than-normal conditions dominated the region at 24-36 months, with wetter-than-normal conditions dominating at longer time scales (radar-based precipitation anomaly estimates for the last 1, 2, 3, 6, 9, 12 months) (low elevation station precipitation maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months) (climate engine model percent of normal precipitation map for the last month: PR and USVI, Caribbean region).
Root zone analyses indicated that soil conditions were dry along the southern coast and immediate northwest coast in PR. Monthly streamflow in PR was mostly near normal. Groundwater on the USVI continued to decline, although some recovery was indicated near the end of the month on St. Thomas (groundwater level graphs for St. Croix, St. Thomas, and St. John). Reports from the USVI indicate that sporadic rainfall territory-wide was mildly recharging ponds and collection containers and increased soil moisture. Vegetation and trees were showing signs of improvement. Moderate drought shrank from 19.7 percent of PR at the end of May to about 8.3 percent on the June 29th USDM map. In the USVI, conditions improved from severe drought to moderate drought on St. John and abnormal dryness on St. Thomas, while severe drought continued on St. Croix.
Western U.S.
As discussed earlier, according to USDM statistics, the percent area of the West in moderate to exceptional drought at the end of June 2021 was exceeded in the 21-year USDM record only by the drought of 2003. According to Palmer Drought Index statistics, the percent area of the West (from the Rockies to the West Coast) in moderate to extreme drought set a 122-year record. This is due to record low precipitation and excessively hot temperatures during the last several years.
June 2021 was much drier than normal across northern portions of the West, while summer monsoon rain gave parts of the Southwest a wetter-than-normal month. June temperatures were near to record warm across the West. April-June 2021 was drier than normal to record dry and warmer than normal to record warm across the region. These anomalies have persisted throughout 2021 and for the last 12 months and are evident in many datasets and indicators, including low elevation station data, high elevation (SNOTEL) data (station precipitation percentiles for last 1, 3, 12 months) (basin precipitation anomalies for last 1, 3, 9 months), and (as seen earlier in this report) SPI and SPEI. The dryness and heat of the last 12 months follow record heat and dryness of the previous 12 months, making the last two years a period of compounded record heat and dryness (maps of 24-month low elevation station percent of normal precipitation, SNOTEL basin percent of normal precipitation, SNOTEL station precipitation percentiles, SPI, SPEI).
Numerous statewide and regional records have resulted from the persistent anomalous heat and dryness. Arizona, California, Nevada, and Utah had the driest July-June 12-month period in the 1895-2021 record, with Idaho, Montana, and Wyoming ranking second driest. Nevada and Utah had the driest July-June 24-month period on record, Arizona had the driest 18-month period on record and sixth driest 24-month period, and California ranked second driest for the July-June 24-month period. Regionwide, the West had the warmest and second driest April-June, second driest and fourth warmest July-June 12-month period, and driest and fifth warmest July-June 24-month period. The excessive and prolonged dryness has given the current drought episode the largest percent area of exceptional drought conditions in the USDM record in Arizona, New Mexico, Nevada, and Utah, and the largest extreme to exceptional drought area on record in California and Nevada.
CONUS State Precipitation Ranks
June 2021 was drier than normal across most of the West, northern and central Plains, and New England, with record dryness occurring locally in parts of the northern Plains and New England. Eighteen states in these regions had a precipitation rank in the driest third of the 127-year historical record for June, including six in the top ten driest category — South Dakota (driest on record), Montana (second driest), Idaho and Maine (both fourth driest), Minnesota (seventh driest), and New Hampshire (tenth driest).
April-June 2021 was drier than normal across the West, northern and central Plains, Upper Midwest, Northeast, Ohio and Tennessee Valleys to Mid-Atlantic states, and southern Florida, with record dryness occurring locally in parts of the West and northern Plains. Twenty-five states in these regions had a precipitation rank in the driest third of the 127-year historical record for April-June, including eight in the top ten driest category — California (second driest); Idaho, Oregon, and Washington (each third driest); Utah (fourth driest); South Dakota (fifth driest); Montana (seventh driest); and Minnesota (ninth driest).
January-June 2021 was drier than normal across the West, northern Plains, Upper Midwest, Northeast, central Appalachians, and southern Florida, with record dryness occurring locally in parts of the West and northern Plains. Twenty-four states in these regions had a precipitation rank in the driest third of the 127-year historical record for January-June, including nine in the top ten driest category — Montana and North Dakota (both fourth driest); Maine, New Hampshire, and South Dakota (each seventh driest); Utah (eighth driest); Idaho and Minnesota (both ninth driest); and Vermont (tenth driest).
July 2020-June 2021 was drier than normal across the western and northern states, with widespread record dryness occurring in the West. Twenty-two states in the West, northern and central Plains, Upper Mississippi Valley, and Northeast had a precipitation rank in the driest third of the 127-year historical record for July-June, including ten in the top ten driest category — Utah, Nevada, California, and Arizona (each driest on record); Wyoming, Montana, and Idaho (each second driest); North Dakota (ninth driest); and South Dakota and New Mexico (both tenth driest).
Agricultural Belts
During June 2021, the Primary Corn and Soybean agricultural belt was generally warmer and drier than normal in the north, near to cooler than normal in the south, with alternating bands of above- and below-normal precipitation in central and southern portions. The month ranked as the 44th wettest and tenth warmest June, regionwide, in the 1895-2021 record.
March marks the beginning of the growing season for the Primary Corn and Soybean agricultural belt. March-June 2021 was warmer than normal in the north and cooler than normal in the south with precipitation having a similar alternating anomaly band pattern as for June. The period ranked as the 58th wettest and 13th warmest March-June, regionwide, on record.
During June 2021, the Spring Wheat agricultural belt was warmer and drier than normal. The month ranked as the second driest and second warmest June, regionwide, in the 1895-2021 record.
March marks the beginning of the growing season for the Spring Wheat agricultural belt. March-June 2021 was also warmer and drier than normal. The period ranked as the second driest and eleventh warmest March-June, regionwide, on record.
As of June 29, drought affected approximately 93 percent of spring wheat production, 72 percent of barley production, 57 percent of the milk cow inventory, 54 percent of the sheep inventory, 38 percent of corn production, 36 percent of hay acreage, 35 percent of the cattle inventory, 33 percent of soybean production, 29 percent of winter wheat production, 20 percent of rice production, 5 percent of cotton production, 4 percent of sorghum production, and 1 percent of peanut production.
June 27 USDA reports indicated that topsoil moisture was short or very short (dry or very dry) across (in the Northeast) 91 percent of New Hampshire, 90 percent of Rhode Island, 80 percent of Vermont, 69 percent of Maine, 62 percent of New York; (in the northern Plains) 90 percent of South Dakota, 75 percent of Minnesota, 66 percent of North Dakota; (in the West) 89 percent of Washington, 86 percent of Oregon, 80 percent of Utah, 78 percent of Montana, 78 percent of New Mexico, 70 percent of California, 67 percent of Wyoming, 64 percent of Idaho, and 60 percent of Nevada. These statistics were above the 5-year and 10-year mean percent areas for all of these states except California. Subsoil moisture was short or very short across 75 percent of California, 62 percent of Idaho, 60 percent of Iowa, 89 percent of Maine, 69 percent of Minnesota, 70 percent of Montana, 65 percent of Nevada, 85 percent of New Hampshire, 91 percent of New Mexico, 52 percent of New York, 78 percent of North Dakota, 86 percent of Oregon, 80 percent of Rhode Island, 87 percent of South Dakota, 69 percent of Utah, 62 percent of Vermont, 76 percent of Washington, and 65 percent of Wyoming. On a national scale, 41 percent of the topsoil moisture and 41 percent of the subsoil moisture were short or very short — these are increases compared to last month. The lack of rain and dry soils have desiccated pastures, with pasture and range condition poor to very poor in 88 percent of Arizona, 45 percent of California, 37 percent of Idaho, 44 percent of Minnesota, 70 percent of Montana, 60 percent of Nevada, 72 percent of New Mexico, 65 percent of North Dakota, 67 percent of Oregon, 68 percent of South Dakota, 30 percent of Texas, 72 percent of Utah, 77 percent of Washington, and 42 percent of Wyoming. Nationwide, 43 percent of the pasture and rangeland, 39 percent of the spring wheat, 21 percent of winter wheat, 9 percent of soybeans, and 8 percent of the corn crop were in poor to very poor condition, and these were all higher than the previous month. On a state by state basis, the percent of the winter wheat in poor to very poor condition was 71 percent for Oregon, 50 percent for South Dakota, 36 percent for Washington, and 32 percent for Texas; values were less than 30 percent for other states. The state by state values for spring wheat in poor to very poor condition were 32 percent for Minnesota, 44 percent for North Dakota, 49 percent for South Dakota, and 70 percent for Washington; Idaho (17 percent) and Montana (28 percent) were below 30 percent. The U.S. Spring Wheat Condition Index computed by the USDA indicates that spring wheat is in the worst condition in 2021 than it has been in the last 21 years.
U.S.-Affiliated Pacific Islands
The NOAA National Weather Service (NWS) offices, the Pacific ENSO Applications Climate Center (PEAC), and partners provided reports on conditions across the Pacific Islands.
In the U.S. Affiliated Pacific Islands (USAPI) (maps — Federated States of Micronesia [FSM], Northern Mariana Islands, Marshall Islands [RMI], Republic of Palau, American Samoa, basinwide), June 2021 was drier-than-normal in the RMI, Palau, southern Marianas, and western and southern parts of the FSM. It was near to wetter than normal elsewhere across Micronesia and in American Samoa.
Monthly precipitation amounts were below the monthly minimum needed to meet most water needs (4 inches in the Marianas and Pago Pago, and 8 inches elsewhere) at Rota (in the Marianas); Ailinglaplap, Kwajalein, and Wotje (Marshalls); and Chuuk and Woleai in the FSM. June precipitation was above the monthly minimums at the rest of the USAPI stations in the FSM, Marianas, RMI, Palau, and American Samoa. The 4- and 8-inch thresholds are important because, if monthly precipitation falls below the threshold, then water shortages or drought become a concern.
The tropical Pacific climatology can experience extremes in precipitation, from very low precipitation during the dry season to very high precipitation during the wet season. This can result in monthly normal precipitation values that are different from the monthly minimum needed to meet most water needs, and this can lead to percent of normal values that seem odd. This was the case during June 2021, which is in the wet season or entering the wet season for most locations in Micronesia. Precipitation was above the monthly minimum but below normal (1981-2010 normal), because the normals are high, at:
- Guam: June 2021 precipitation 5.08 inches, June normal mean 7.09 inches, June normal median 6.18 inches
- Yap: June 2021 precipitation 10.35 inches, June normal mean 13.20 inches, June normal median 12.04 inches
- Kapingamarangi: June 2021 precipitation 9.95 inches, June normal mean 13.17 inches, June normal median 13.78 inches
- Majuro: June 2021 precipitation 9.28 inches, June normal mean 10.93 inches, June normal median 11.01 inches
| Station Name | Jul 2020 | Aug 2020 | Sep 2020 | Oct 2020 | Nov 2020 | Dec 2020 | Jan 2021 | Feb 2021 | Mar 2021 | Apr 2021 | May 2021 | Jun 2021 | Jul- Jun |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 65% | 95% | 167% | 92% | 127% | 182% | 114% | 156% | 223% | 55% | 244% | 60% | 122% |
| Guam NAS | 81% | 86% | 87% | 146% | 140% | 157% | 102% | 33% | 130% | 119% | 210% | 82% | 91% |
| Kapingamarangi | 40% | 36% | 9% | 15% | 31% | 38% | 65% | 63% | 78% | 150% | 129% | 72% | 57% |
| Koror | 55% | 164% | 62% | 170% | 88% | 142% | 102% | 166% | 119% | 287% | 178% | 56% | 112% |
| Kosrae | 96% | 87% | 114% | 149% | 177% | 185% | 188% | 141% | 194% | 106% | 154% | 194% | 126% |
| Kwajalein | 89% | 54% | 144% | 140% | 115% | 60% | 74% | 75% | 264% | 174% | 126% | 67% | 105% |
| Lukonor | 83% | 81% | 134% | 105% | 102% | 219% | 146% | 180% | 84% | 134% | 238% | 105% | 116% |
| Majuro | 115% | 85% | 101% | 176% | 112% | 147% | 150% | 57% | 228% | 135% | 285% | 84% | 135% |
| Pago Pago | 201% | 179% | 228% | 201% | 160% | 113% | 132% | 141% | 91% | 76% | 80% | 212% | 124% |
| Pohnpei | 62% | 98% | 120% | 121% | 169% | 168% | 147% | 65% | 216% | 77% | 152% | 141% | 125% |
| Saipan | 57% | 68% | 74% | 104% | 88% | 193% | 91% | 122% | 46% | 77% | 120% | 158% | 88% |
| Yap | 51% | 72% | 81% | 104% | 196% | 200% | 201% | 139% | 189% | 316% | 109% | 86% | 118% |
| Station Name | Jul 2020 | Aug 2020 | Sep 2020 | Oct 2020 | Nov 2020 | Dec 2020 | Jan 2021 | Feb 2021 | Mar 2021 | Apr 2021 | May 2021 | Jun 2021 | Jul- Jun |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 7.77" | 12.20" | 19.61" | 10.57" | 13.45" | 20.47" | 11.56" | 11.29" | 18.55" | 6.86" | 27.53" | 7.00" | 166.86" |
| Guam NAS | 8.26" | 12.68" | 10.96" | 16.75" | 10.33" | 8.02" | 4.11" | 1.01" | 2.70" | 3.02" | 7.14" | 5.08" | 90.06" |
| Kapingamarangi | 5.59" | 2.94" | 0.86" | 1.19" | 2.83" | 3.77" | 5.92" | 5.86" | 8.91" | 20.44" | 15.53" | 9.95" | 83.79" |
| Koror | 10.13" | 22.13" | 7.28" | 20.11" | 9.97" | 15.82" | 10.42" | 14.23" | 8.84" | 21.03" | 21.06" | 9.87" | 170.89" |
| Kosrae | 14.26" | 12.41" | 16.16" | 16.25" | 24.52" | 29.87" | 31.36" | 18.28" | 31.20" | 18.63" | 27.37" | 28.33" | 268.64" |
| Kwajalein | 8.82" | 5.24" | 15.51" | 15.64" | 12.95" | 4.02" | 2.34" | 1.97" | 6.21" | 9.17" | 8.45" | 4.61" | 94.93" |
| Lukonor | 13.18" | 11.35" | 13.63" | 11.83" | 9.23" | 24.71" | 12.29" | 16.11" | 7.81" | 15.21" | 27.86" | 12.26" | 175.47" |
| Majuro | 12.85" | 9.97" | 11.25" | 22.35" | 14.99" | 16.71" | 11.58" | 3.89" | 15.00" | 12.71" | 28.81" | 9.28" | 169.39" |
| Pago Pago | 11.17" | 9.63" | 14.90" | 18.63" | 16.25" | 14.55" | 17.62" | 16.86" | 9.68" | 7.14" | 7.71" | 11.32" | 155.46" |
| Pohnpei | 9.53" | 13.99" | 15.02" | 18.49" | 25.13" | 26.95" | 19.38" | 6.24" | 28.50" | 14.18" | 30.38" | 20.95" | 228.74" |
| Saipan | 5.11" | 8.88" | 7.46" | 11.08" | 4.95" | 7.43" | 2.30" | 3.15" | 0.86" | 2.02" | 2.85" | 5.71" | 61.8" |
| Yap | 7.71" | 10.61" | 10.98" | 12.71" | 17.27" | 16.99" | 12.85" | 7.24" | 8.63" | 17.78" | 8.59" | 10.35" | 141.71" |
| Station Name | Jul 2020 | Aug 2020 | Sep 2020 | Oct 2020 | Nov 2020 | Dec 2020 | Jan 2021 | Feb 2021 | Mar 2021 | Apr 2021 | May 2021 | Jun 2021 | Jul- Jun |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chuuk | 11.98" | 12.86" | 11.71" | 11.51" | 10.61" | 11.25" | 10.10" | 7.25" | 8.32" | 12.47" | 11.30" | 11.66" | 136.77" |
| Guam NAS | 10.14" | 14.74" | 12.66" | 11.44" | 7.38" | 5.11" | 4.01" | 3.03" | 2.07" | 2.53" | 3.40" | 6.18" | 99.09" |
| Kapingamarangi | 14.15" | 8.13" | 9.93" | 8.19" | 9.27" | 9.84" | 9.15" | 9.27" | 11.43" | 13.64" | 12.08" | 13.78" | 145.85" |
| Koror | 18.53" | 13.50" | 11.77" | 11.84" | 11.39" | 11.16" | 10.18" | 8.56" | 7.44" | 7.32" | 11.83" | 17.48" | 152.90" |
| Kosrae | 14.91" | 14.22" | 14.22" | 10.94" | 13.83" | 16.11" | 16.67" | 12.93" | 16.06" | 17.51" | 17.75" | 14.64" | 213.87" |
| Kwajalein | 9.87" | 9.74" | 10.74" | 11.18" | 11.28" | 6.66" | 3.16" | 2.64" | 2.35" | 5.26" | 6.72" | 6.93" | 90.41" |
| Lukonor | 15.93" | 14.04" | 10.15" | 11.32" | 9.08" | 11.27" | 8.41" | 8.93" | 9.26" | 11.31" | 11.69" | 11.65" | 151.36" |
| Majuro | 11.17" | 11.69" | 11.17" | 12.73" | 13.44" | 11.39" | 7.74" | 6.88" | 6.58" | 9.42" | 10.11" | 11.01" | 125.25" |
| Pago Pago | 5.55" | 5.38" | 6.53" | 9.26" | 10.14" | 12.84" | 13.34" | 12.00" | 10.68" | 9.39" | 9.66" | 5.33" | 125.57" |
| Pohnpei | 15.43" | 14.26" | 12.55" | 15.27" | 14.83" | 16.08" | 13.18" | 9.55" | 13.17" | 18.41" | 19.96" | 14.81" | 182.36" |
| Saipan | 8.91" | 13.13" | 10.09" | 10.62" | 5.61" | 3.85" | 2.53" | 2.59" | 1.89" | 2.63" | 2.38" | 3.62" | 70.25" |
| Yap | 15.08" | 14.82" | 13.50" | 12.18" | 8.83" | 8.51" | 6.39" | 5.19" | 4.56" | 5.63" | 7.85" | 12.04" | 120.31" |
As measured by percent of normal precipitation, Saipan was wetter than normal in the short term (June and the last 3 months [April-June 2021]) but drier than normal in the long term (year to date [January-June 2021] and last 12 months [ July 2020-June 2021]). Guam and Kapingamarangi were wetter than normal for April-June but drier than normal at the other 3 time periods. Airai (Palau International Airport), Chuuk, Kwajalein, Majuro, and Yap were drier than normal for June but wetter than normal for the other 3 time periods. Kosrae, Lukunor, Pago Pago, and Pohnpei were near to wetter than normal at all 4 time periods.
Based on percent of normal average (instead of normal median values), in the Marianas Islands, precipitation during June was generally below normal across the islands. Below-normal conditions continued at the stations in the central islands while the northern-most and southern-most plotted stations wetter than normal at the 2-month and longer time scales (percent of normal precipitation maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months).
In the Marshall Islands, June, May-June, and April-June were drier than normal at the northern and western islands, but wetter than normal at the southern and eastern islands. Wetter-than-normal conditions dominated at the 4-month time scale, a mixed anomaly pattern dominating at longer time scales (percent of normal precipitation maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months).
![0-10 cm [0-4 inches] depth](/monitoring-content/sotc/drought/2021/06/sport.vsm0-10percent_20210630_00z_conus.gif){kind=link}
![0-40 cm [0-16 inches] depth](/monitoring-content/sotc/drought/2021/06/sport.vsm0-40percent_20210630_00z_conus.gif){kind=link}
![0-100 cm [0-39 inches] depth](/monitoring-content/sotc/drought/2021/06/sport.vsm0-100percent_20210630_00z_conus.gif){kind=link}
![0-200 cm [0-79 inches] depth](/monitoring-content/sotc/drought/2021/06/sport.vsm0-200percent_20210630_00z_conus.gif){kind=link}
![0-10 cm [0-4 inches] depth](/monitoring-content/sotc/drought/2021/06/sport-ak.vsmperc0-10_20210630_0400akdt_ak.gif){kind=link}
![0-40 cm [0-16 inches] depth](/monitoring-content/sotc/drought/2021/06/sport-ak.vsmperc0-40_20210630_0400akdt_ak.gif){kind=link}
![0-100 cm [0-39 inches] depth](/monitoring-content/sotc/drought/2021/06/sport-ak.vsmperc0-100_20210630_0400akdt_ak.gif){kind=link}
![0-200 cm [0-79 inches] depth](/monitoring-content/sotc/drought/2021/06/sport-ak.vsmperc0-200_20210630_0400akdt_ak.gif){kind=link}
According to the June 30th USDM produced for the USAPI, drought transitioned to abnormally dry conditions at Wotje, with abnormally dry conditions ending at Kapingamarangi. The rest of the USAPI islands were free of drought and abnormal dryness. Storage in the Majuro reservoir steadily decreased during the month, falling from a peak of about 34.9 million gallons and ending the month at 29.7 million gallons, which is just above the 28.8 million gallon threshold for concern. The National Weather Service office in Guam issued one Drought Information Statement (DGT) for drought in June (on June 11) discussing the conditions in the USAPI, and this was the final DGT for the 2021 dry season. The continuation of ENSO-neutral conditions allowed the Inter-Tropical Convergence Zone (ITCZ) to bring converging winds and adequate rainfall to most of Micronesia, aided by the seasonal return of the Tropical Upper-Tropospheric Trough (TUTT). Conditions continued to improve with water catchment levels adequate across the northern Marshall Islands from off and on trade-wind showers, but residents continued to conserve water due to monthly rainfall being less than 8 inches.
June 2021 precipitation ranks were low at several stations. Wet conditions during previous months moderated ranks for longer time periods at some, while long-term dryness was still evident at others:
- Kapingamarangi: June 2021 was the 16th driest (16th wettest) June (out of a 31-year record), but the last 11 and 12 months (August-June and July-June) were still the second driest on record
- Saipan: ninth wettest June, but fifth driest July-June (32-year record)
- Chuuk: third driest June (70 years)
- Woleai: fifth driest June (39 years)
- Ailinglaplap: fifth driest June and second driest May-June (38 years), but second wettest July-June through October-June (last 9 through 12 months)
- Kwajalein: sixth driest June (70 years)
- Wotje: eighth driest June and seventh driest May-June (37 years)
The following analysis of historical data for the USAPI stations in the Global Historical Climatology Network-Daily (GHCN-D) dataset, augmented with fill-in data from the 1981-2010 Normals, helps put the current data into historical perspective by computing ranks based on the period of record. The table below lists the precipitation ranks for June 2021, January-June 2021 (last 6 months), and July 2020-June 2021 (the last 12 months). Some stations have a long period of record and their dataset is fairly complete, while other stations have a shorter period of record and the dataset has some missing data.
| Station | June 2021 | Jan-Jun 2021 | Jul 2020-Jun 2021 | Period of Record | |||
|---|---|---|---|---|---|---|---|
| Rank | Years | Rank | Years | Rank | Years | ||
| Ailinglaplap | 5 | 38 | 33 | 38 | 34 | 35 | 1981-2021 |
| Chuuk | 3 | 70 | 59 | 70 | 65 | 70 | 1951-2021 |
| Fananu | -- | 8 | -- | 4 | -- | 3 | 2003-2021 |
| Guam | 19 | 65 | 23 | 64 | 20 | 64 | 1957-2021 |
| Jaluit | 32 | 37 | 14 | 37 | 10 | 35 | 1981-2021 |
| Kapingamarangi | 16 | 31 | 9 | 25 | 2 | 18 | 1962-2021 |
| Koror (Airai) | 7 | 70 | 67 | 70 | 64 | 69 | 1951-2021 |
| Kosrae | 52 | 54 | 39 | 43 | 32 | 35 | 1954-2021 |
| Kwajalein | 6 | 70 | 30 | 69 | 30 | 69 | 1952-2021 |
| Lukonor | 24 | 37 | 35 | 37 | 23 | 24 | 1981-2021 |
| Majuro | 20 | 68 | 62 | 67 | 64 | 67 | 1954-2021 |
| Mili | 31 | 37 | 37 | 37 | -- | 32 | 1981-2021 |
| Nukuoro | 37 | 39 | 25 | 38 | 19 | 36 | 1981-2021 |
| Pago Pago | 47 | 56 | 32 | 55 | 51 | 55 | 1966-2021 |
| Pingelap | 37 | 39 | 27 | 36 | 27 | 33 | 1981-2021 |
| Pohnpei | 56 | 70 | 68 | 70 | 69 | 70 | 1951-2021 |
| Saipan | 33 | 41 | 18 | 40 | 5 | 32 | 1981-2021 |
| Ulithi | -- | 37 | -- | 35 | -- | 33 | 1981-2021 |
| Utirik | -- | 15 | -- | 9 | -- | 5 | 1985-2020 |
| Woleai | 5 | 39 | 30 | 31 | 19 | 24 | 1968-2021 |
| Wotje | 8 | 37 | 10 | 37 | 25 | 33 | 1981-2021 |
| Yap | 25 | 70 | 64 | 70 | 60 | 70 | 1951-2021 |
SPI values for seven time periods for Pacific Islands, computed by the Honolulu NWS office.
NOAA Regional Climate Centers
More information, provided by the NOAA Regional Climate Centers and others, can be found below.
Southeast
As noted by the Southeast Regional Climate Center, June temperatures were near average across much of the Southeast region while precipitation varied across the region. The driest locations were found across much of Virginia, western North Carolina, and central Florida. Monthly precipitation totals ranged from 70 to less than 25 percent of normal across these locations. Indeed, Danville, VA (1916-2021) observed its 6th driest June with only 1.2 inches (30 mm) of precipitation, which was more than 2.7 inches (68 mm) below average. In contrast, the wettest locations were located across most of Alabama, central Georgia, eastern North Carolina, and Puerto Rico.
Drought conditions improved across all of the Southeast region for June. Adequate rainfall fell in the driest areas; consequently, the severe drought (D2) was eliminated in the Carolinas by the end of June, with just a few pockets of moderate drought (D1) embedded in an area of abnormally dry conditions in central Virginia, central North Carolina and eastern South Carolina. Moderate drought (D1) was eliminated in Florida; however, pockets of abnormally dry conditions (D0) remain. Drought conditions improved across Puerto Rico as well, with an area of moderate drought (D1) in the southern part of the island ringed by an area of abnormally dry conditions (D0). The citrus growing region in Florida experienced warm and dry conditions; however, normal grove activities continued with extra irrigation. Rainfall in the northern part of the Florida Peninsula put disease and pest pressures on the peanut crop. Cotton maturation, however, remained behind schedule, due to the dry conditions early in the growing season. Rain continued to improve pasture quality, and cattle remained in good condition throughout the state. Frequent rainfall events in Georgia helped maintain good overall crop conditions. Early corn began to mature but corn rust was noted in a few of the wetter counties. Southern corn rust was also detected in some fields near coastal Alabama due to rains from Tropical Storm Claudette. Warm temperatures and adequate rainfall improved crop conditions across South Carolina. However, heavy amounts of localized rain increased the presence of annual summer weeds in pastures, but cattle remained in mostly good condition.
South
As explained by the Southern Regional Climate Center, June 2021 featured above-normal rainfall, leading to drought reduction and multiple flooding events. Across the Southern region, temperatures in June were in the middle third of the historical values for the 1895-present period of record. Most states were wetter than the historical median, except Tennessee which was near the median, giving the Southern region an overall average of 4.65 inches (118 mm), 28th wettest all-time.
Continued improvement in drought conditions was the rule for Texas and Oklahoma, while the other portions of the Southern region remained drought-free. Overall drought coverage decreased from slightly more than 10% of the region to slightly less than 5%, and exceptional drought (D4) was eradicated for the first time in over ten months. About half of the Trans Pecos area remained in drought, including some extreme drought (D3), and lingering areas of drought remained in isolated parts of Oklahoma, along the Texas-New Mexico border, and along portions of the Pecos and Rio Grande rivers.
Midwest
As described by the Midwest Regional Climate Center, June temperatures were above normal for much of the Midwest region while precipitation varied considerably across the region. The regionwide average temperature was 71.5 degrees F (21.9 C), which was 2.5 degrees F (1.4 C) above normal. This tied for the 10th warmest June since 1895, and ranked as the 2nd warmest June in the last 30 years. Five states were drier than normal and four were wetter than normal. Statewide Minnesota was at just 39 percent of normal precipitation in June and Iowa was at 59 percent of normal. Minnesota had the 4th driest June on record (1895-2021) while Michigan ranked as the 16th wettest in its history. It was the driest June in Minnesota since 1961.
Warm and drier conditions in parts of the Upper Midwest led to expansion of drought conditions which covered about a third of the region in June. Nearly all of the drought was in the northern half of the region. Severe drought peaked at 11 percent of the region mid-month. A small area of extreme drought emerged along the Wisconsin-Illinois border near Lake Michigan. Some small pockets of abnormally dry conditions were scattered across the southern half of the region. As of the June 29th USDM, more than 15 million people were estimated to be living in drought-affected areas of the Midwest.
Northeast
As explained by the Northeast Regional Climate Center, the Northeast had its fourth warmest June since 1895, with an average temperature of 68.0 degrees F (20.0 degrees C), 2.5 degrees F (1.4 degrees C) above normal, and the month was drier than normal for the region, with the Northeast receiving 3.23 inches (82.04 mm) of precipitation, 73 percent of normal. State precipitation ranged from 43 percent of normal in Maine to 104 percent of normal in West Virginia, the only wetter-than-normal state. This June ranked as Maine's fourth driest June on record, while New Hampshire had its 10th driest June.
The USDM released on June 3 showed 3 percent of the Northeast in moderate drought (D1) and 37 percent as abnormally dry (D0). During June, above-normal temperatures, below-normal precipitation, low streamflow and groundwater levels, and little soil moisture led to worsening conditions in New England and New York. Severe drought was introduced in Maine and northern New Hampshire. Moderate drought was introduced on Cape Cod, Massachusetts, and expanded in northern New England and northern New York. Abnormal dryness expanded in Maine, Massachusetts, Vermont, and New York. However, southern parts of the Northeast, including portions of West Virginia, Maryland, and New Jersey were wetter, easing abnormal dryness. The June 29 USDM released on July 1 showed 4 percent of the Northeast in severe drought, 17 percent in moderate drought, and 21 percent as abnormally dry. Vermont's record for longest drought duration grew to 54 straight weeks as of June 29.
The dry conditions had several impacts. Portions of New England and New York saw near-record low streamflow and/or groundwater levels, with daily low streamflow records set on several waterways in Maine and New Hampshire. Water levels of some Maine reservoirs were lower than usual, possibly affecting loon productivity and curtailing some boating flows. Water levels were also well below average on Lake Ontario and Lake Champlain. Eighty-six community water systems in New Hampshire had water restrictions in place as of June 30, with 78 of them having mandatory restrictions. In Maine, the South Berwick Water District enacted mandatory water restrictions due to low water levels in their four wells, while several other public water systems had voluntary water restrictions in place. A water watch was issued for Lowville, New York, as water levels in the village's water tank were lower than usual. Several wells in Maine and Vermont ran dry or were experiencing water shortages. Farmers in Maine and New Hampshire noted the need to irrigate but experienced some water shortages and slow crop growth. Some New York growers reported stressed corn, reduced productivity of second cutting of hay, and having to replant soybeans. Dry conditions in northern New England continued to pose an increased risk of fires starting easily and burning deeply, with both states seeing more fires than usual this spring. Two fire chiefs in Vermont delayed some training sessions in order to save water in case it was needed to fight fires. A New Hampshire fire chief purchased a water tank that allows the department to bring their own water supply when fighting fires in rural locations instead of relying on waterways that are running low. The dry conditions allowed large populations of gypsy moth caterpillars to proliferate in the Northeast, further taxing trees experiencing drought stress, and contributed to an outbreak of browntail moth caterpillars in Maine.
High Plains
As summarized by the High Plains Regional Climate Center, oppressive heat and dryness caused drought conditions to continue to intensify throughout the High Plains in June. Above-normal temperatures were felt across nearly the entire region and, for the most part, June was dry across the High Plains. Monthly precipitation totals of less than 50 percent of normal were widespread, with pockets of South Dakota, Wyoming, and Nebraska receiving 25 percent of normal precipitation at best. This resulted in several locations breaking into the top 10 driest Junes on record. For instance, Mobridge, South Dakota tied for its 2nd driest June, recording a paltry 0.38 inch (10 mm) of precipitation (period of record 1911-2021). The dryness drove up temperatures and exacerbated drought conditions across the region. On the other hand, southwestern and central Colorado, as well as pockets of North Dakota and eastern Kansas, had a wet June with precipitation exceeding 150 percent of normal.
Impacts were being felt in several sectors across multiple states in the region. The continuation of poor pasture and range conditions across the Dakotas and Wyoming has made it increasingly difficult to find forage for livestock, which has forced producers to sell off their herds. The availability of high-quality water supplies for livestock was also very limited. Soil moisture was depleted across the northern part of the region. For instance, according to the June 29th USDA Weekly Weather and Crop Bulletin, 90 percent of South Dakota's topsoil moisture and 87 percent of its subsoil moisture were rated short to very short. Spring wheat and barley were not only faring poorly in the Dakotas, but nationwide as well, as both crops were in the worst condition ever recorded up to this point in the season since at least 2001. Corn and soybean conditions began to deteriorate throughout the Dakotas as well, as curling corn leaves and short soybeans were reported. Corn will be entering the silking stage very soon in this region, which is a critical growth stage due to the amount of moisture needed. If ample precipitation is not received during this stage, yield is likely to be lower.
Ongoing drought conditions across the Northern Plains also contributed to extremely high temperatures. While heatwaves are certainly not uncommon in June, the intensity of the heat that early in the summer was unusual. Several locations throughout the Dakotas reached 100.0 degrees F (37.8 degrees C) the first week of the month. However, it was the heatwave in late June across the northern U.S. that was highly impactful, especially across the Pacific Northwest. Numerous all-time high temperature records were shattered across Washington and Oregon, and many were left vulnerable to the heat due to the lack of air conditioning, resulting in over 100 deaths. It is worth mentioning that the heatwave also impacted western Canada. Lytton, British Columbia set an unofficial record high for Canada at 121.3 degrees F (49.6 degrees C). While the number varies by source, several hundred deaths were blamed on the heatwave in British Columbia.
Upper Missouri Basin mountain snowpack completely melted out in June. Due to drought conditions in the upper Basin, the U.S. Army Corps of Engineers Missouri River Water Management Division announced that they will reduce navigation flow support for the second half of the navigation season. However, they do expect that the length of the navigation flow support season will be a full eight months, ending December 1. Below-normal precipitation continued to cause streamflows to dwindle throughout the region. The lowest streamflows could be found across much of North Dakota, eastern South Dakota, western Colorado, and along the northern, southern, and western borders of Wyoming. However, streamflows were faring well across much of Kansas and eastern Colorado where precipitation has been more plentiful.
Both improvements and degradations in drought conditions occurred in the High Plains in June. According to the USDM, the area experiencing drought (D1-D4) increased from approximately 48 percent to 55 percent over the course of the month. However, the area experiencing abnormal dryness and drought (D0-D4) decreased slightly from about 69 percent to 68 percent. Drought conditions intensified in parts of Wyoming, South Dakota, and Nebraska. New areas of extreme drought (D3) were introduced to northeastern Wyoming and southeastern South Dakota/northeastern Nebraska, while the area of D3 in north-central South Dakota expanded southward. Severe drought (D2) expanded throughout much of Wyoming, as well as eastern South Dakota into northeastern Nebraska. Moderate drought (D1) spread across portions of north-central Nebraska and the Nebraska Panhandle and filled in remaining areas of eastern South Dakota that had not been in drought. Abnormal dryness (D0) expanded into central and southern Nebraska down into north-central Kansas. All of these areas have experienced below-normal precipitation going back to April. Several areas also experienced improvement in conditions. Much-needed rain fell in southwestern North Dakota/northwestern South Dakota, improving D3 areas to D2 or D1. Heavy rains also improved D1 conditions along the Continental Divide in Colorado, and D0 was eradicated across much of eastern Colorado and southern Kansas.
West
As described by the Western Regional Climate Center, June was generally warmer and drier than normal across the Western region. June 2021 will be remembered in the West for the historic heat wave that shattered temperature records throughout the greater Pacific Northwest and Intermountain West. An extremely anomalous dome of hot air formed beneath an amplified and stationary Omega blocking pattern in the mid-troposphere. The heat dome led to many locations breaking their previous all-time maximum temperatures (see notable events). Temperature anomalies during June were above average (4-6 F; 2-3 C) throughout the southern tier of the West, with the northern tier experiencing well-above average conditions (6-8 F; 3-4 C), largely owing to the late June heat wave.
Precipitation throughout the West was generally well-below normal with several exceptions. The highly amplified flow during the late June heatwave brought welcome monsoon precipitation to the Southwest, leading to a small region of above normal precipitation. Drizzle from marine stratus helped San Francisco to its 6th wettest June with 0.57 in. (14.5 mm) of precipitation or 335% of normal. Dry records were common in the northern Intermountain West. Pocatello, ID received 0.01 in. (2 mm) of precipitation (1% of normal), making June its driest since records began 83 years ago. Bozeman, MT recorded 0.23 in. (5.8 mm; 10% of normal) of rainfall, its driest June in 77 years.
Sea surface temperatures (SST) north of the Hawaiian Islands were 0-1.5 F (0-0.8 C) above normal, with colder SST anomalies (-1.5 F-0 F (-0.8 C-0 C)) below normal located south and southeast of the islands. Temperatures on the Hawaiian Islands in June were near-normal, with many long-record stations observing mean temperatures near the long-term mean. Despite being the start of the Hawaiian dry season, June precipitation was below average at Honolulu, HI with 0.06 in. (1.5 mm; 12% of normal) making for the 10th driest June since records began in 1940.
June in Alaska was relatively quiet at the monthly scale, but eventful from the perspective of individual events. Modest thunderstorm activity and lightning-ignited wildfires were kept at bay by frequent showers and no sustained warm weather. The June total of 73,000 acres burned was the least amount burned in June since 2014, while the seasonal total through the end of June was the lowest since 2008. The late June heat dome and omega blocking pattern did impact Alaska, with several daily records begin set. The remainder of Alaskan Bering sea ice melted out by mid-month, while daily ice extent in the Chukchi was 103% of the 1991-2020 median.