Issued 12 May 2022
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 33% of the contiguous United States as of the end of April 2022, a decrease of about -6% from last month. About 4% of the contiguous U.S. fell in the severely to extremely wet categories.
- About 46% of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of April
- 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 May 3, 2022, 53.77% of the contiguous U.S. (CONUS) (45.01% of the U.S. including Alaska, Hawaii, and Puerto Rico) was classified as experiencing moderate to exceptional (D1-D4) drought.
Detailed Drought Overview
The upper-level circulation during April 2022 was very active with several shortwave troughs and closed lows moving through a strong westerly jet stream flow. They moved through a long-wave pattern in which troughs dominated the flow over the northern tier states and ridging occurred frequently over the southern tier states. This resulted in a monthly upper-level circulation that was fairly zonal (west-to-east) across the CONUS. The dominance of troughing to the north and ridging to the south also created a monthly upper-level anomaly field that enhanced the strength of the westerly jet stream component, contributing to the number and frequency of storms moving across the country. It also resulted in monthly surface temperatures that were cooler than normal from the Pacific Northwest to Great Lakes and warmer than normal across the Southwest to southern Plains. Surface low pressure systems and fronts associated with the Pacific upper-level systems spread rain and snow across the Northwest to northern Plains, and rain across parts of the Deep South, Southeast, and Northeast. Monthly precipitation totals were above normal in these areas. The frontal systems also generated several bouts of severe weather from the Plains to Southeast. Cooler air behind the fronts also was responsible for a cooler-than-normal month from the Upper and Mid-Mississippi Valley to Southeast. The weather systems mostly missed the Southwest to southern and central Plains, where drier air dominated and precipitation was much below normal to record dry. The month was also drier than normal across parts of the Southeast and Ohio Valley to Mid-Atlantic coast.
With above-normal precipitation falling over some drought areas, drought or abnormal dryness contracted or was reduced in intensity in parts of the Pacific Northwest, Great Plains, Mississippi Valley, Northeast, and Southeast, as well as Hawaii. Those areas missing this month's beneficial rains saw expansion or intensification of drought or abnormal dryness and included the Southwest to southern and central Plains, plus other parts of the Pacific Northwest, Southeast, and Mid-Atlantic states, as well as Puerto Rico. Drought contraction exceeded expansion with the USDM-based national moderate-to-exceptional drought footprint across the CONUS decreasing from 58.0 percent at the end of March to 53.8 percent at the end of April (from 48.6 percent to 45.0 percent for the 50 States and Puerto Rico). But the most intense categories of drought (extreme to exceptional) increased in area from 17.1 percent to 18.5 percent for the CONUS (from 14.3 percent to 15.5 percent for the 50 States and Puerto Rico). According to USDM statistics, 40 percent or more of the CONUS has been in moderate drought or worse for the last 85 weeks. This is a record in the 22-year USDM history. The previous record was 68 consecutive weeks (June 19, 2012 to October 1, 2013).
According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 45.8 percent of the CONUS was in moderate to extreme drought at the end of April, which is less than the end of March. The percent area of the CONUS in moderate to extreme drought has hovered between roughly 35 and 53 percent for the last 20 months (since September 2020).
The impacts of the drought can be seen in several indicators, especially in the West, Plains, and Atlantic Coast. These include:
- dry soils (GRACE surface and root zone, VIC, CPC [anomaly, percentile], NLDAS, and Leaky Bucket models; and crop CASMA topsoil and subsoil anomaly, crop CASMA topsoil and subsoil categorical, SPoRT surface and deeper layer, USDA and SMOS observations);
- low ground water (GRACE, USGS) and springwater levels;
- some low streamflow levels (USGS station and huc maps);
- high evapotranspiration (ESI) (1-, 2-, and 3-month EDDI);
- poor vegetation (VegDRI, VCI, pasture and rangeland); and
- the Quick Drought Response Index (QuickDRI).
- Many reservoir levels were low and falling in western Texas and much of the West (California; Washington; Oregon map 1, 2, 3, 4, 5; Idaho map 1, 2, 3; Southwest map 1, 2, 3, 4, 5, 6, 7, 8, 9; westwide station percentile and station and basin percent of average map), with many at or near record low levels.
- The weather systems did little to improve western mountain snowpack. Snow water content (SWE) and snow depth improved slightly in the Pacific Northwest and northern Rockies, but continued to decline in southern areas. Mountain snowpack in the West was low and steadily declining (percentile and percent of average), especially outside of the Pacific Northwest.
- The month started with numerous large wildfires burning in the southern and central Plains (especially Oklahoma and Texas), along the Gulf Coast states, and in the Appalachians (Kentucky and Tennessee). The number of large wildfires decreased in these areas as the month progressed, but several developed in the Southwest during the last half of the month (wildfire maps for April 1, 6, 11, 19, 22, 25, 30). As of April 29, over 21,000 fires had burned over one million acres nationwide; both of these statistics are about one and a half times the ten-year average for this time of year.
Drought conditions at the end of April, as depicted on the May 3, 2022 USDM map, included the following core drought and abnormally dry areas:
- Moderate (D1) to severe (D2) drought extended from the West Coast to Rocky Mountains and into the adjacent Great Plains, with a large areas of extreme (D3) and pockets of exceptional (D4) drought. April precipitation was above normal across much of the Pacific Northwest and parts of the northern Rockies, but below normal across the southern half of the West and in parts of Montana, with parts of the Southwest (Four Corners states) experiencing a record dry April (low-elevation precipitation anomaly map for April; high-elevation SNOTEL station and basin precipitation anomaly maps for April; high-elevation SNOTEL station precipitation percentile map for April). In spite of the April precipitation, much of the West continued to be drier than normal at longer time scales (low-elevation precipitation anomaly maps for last 2, 3, 4, 6, 7, 9, 10, 12 months; high-elevation SNOTEL station and basin precipitation anomaly maps for last 4, 7, 12 months; high-elevation SNOTEL station precipitation percentile maps for last 4, 7, 12 months). Westwide, April 2022 ranked as the 79th driest (50th wettest) April in the 128-year record, but January-April 2022 still ranked as the third driest January-April and May 2021-April 2022 ranked as the 17th driest such 12-month period. The percent area of the West experiencing moderate to exceptional drought, according to USDM statistics, increased slightly from 88.9 percent at the end of March to 91.3 percent at the end of April. However, the percent area of the West (from the Rockies to the West Coast) in moderate to extreme drought (based on the Palmer Drought Index) fell sharply, dropping to 75.2 percent at the end of April 2022.
- Moderate to exceptional drought continued in the Great Plains, especially in the southern portions, with drought expansion/intensification occurring next to drought contracting or decreasing in intensity. In the central to northern Plains, drought contracted in the north but expanded in the south, with the moderate to exceptional drought area decreasing slightly from 77.9 percent at the end of March to 75.1 percent at the end of April. In the southern Plains, drought generally increased in western and central portions but decreased in eastern and far southern portions. Overall, contraction was greater than expansion, so the moderate to exceptional drought area shrank from 85.7 percent at the end of March to 79.3 percent at the end of April, but the extreme to exceptional drought area increased from 39.9 percent to 52.1 percent. In the Lower Mississippi Valley, moderate to extreme drought fell from 55.0 percent at the end of March to 22.9 percent at the end of April. Taken together, the southern Plains and Lower Mississippi Valley (South Region) saw moderate to exceptional drought decrease from 68.5 percent at the end of March to 53.7 percent at the end of April.
- Moderate to severe drought continued in the Midwest, but the drought area shrank from 10.2 percent at the end of March to 1.5 percent at the end of April, remaining mostly in western and northern Iowa.
- In the Northeast, severe drought ended but moderate drought continued, with the regional drought area decreasing from 3.1 percent at the end of March to 1.4 percent at the end of April.
- In the Southeast, the total moderate to severe drought area shrank from 19.7 percent at the end of March to 16.1 percent at the end of April, but the severe drought area increased from 0.6 percent to 2.6 percent.
- Moderate to extreme drought in Hawaii contracted from 78.7 percent at the end of March to 47.1 percent at the end of April.
- In the Caribbean, moderate drought shrank from 4.7 percent of Puerto Rico at the end of March to 3.4 percent at the end of April, while in the U.S. Virgin Islands (USVI), severe drought continued on St. Croix, and moderate drought improved to abnormal dryness on St. John and St. Thomas.
In the U.S.-Affiliated Pacific Islands (USAPI), compared to last month:
- extreme drought improved to severe drought at Wotje in the Marshall Islands;
- abnormal dryness ended at Kapingamarangi, Ulithi, and Yap (Federated States of Micronesia); and
- moderate drought and abnormal dryness ended in the Marianas.
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 much of the Southwest (from southern California to the Four Corners states) and southern to central Plains, expanding or intensifying long-term drought (PHDI maps for April compared to March). Short-term wet conditions occurred over the Pacific Northwest, decreasing long-term drought; from the northern Plains to Great Lakes, decreasing drought in some areas and increasing long-term wet conditions in others; and over the Northeast, increasing 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. Dryness covered most of the West at the 3-, 6-, and 24-month time scales, most of the Southwest at the 1- and 2-month time scales, and large parts of the West at the 9- and 12-month time scales. Much of the southern and central Plains was dry at all time scales, especially the western portions, with the dryness extending along the Gulf of Mexico coast and Lower Mississippi Valley, especially at 6 to 9 months. Much of the Atlantic coast from the Carolinas to Delaware was dry at 3 to 12 months, with parts dry at 1 and 2 months, and the dryness extended to the southern New England coast at 6 months. Dryness covered parts to much of the southern to central Appalachians to eastern Ohio Valley at 1 to 3 months. Parts of the Upper Mississippi Valley were dry at 12 to 24 months. Northern New England was dry at 24 months. Wet conditions dominate the northern Plains at 1 to 9 months, the Pacific Northwest at 1 month, coastal Washington at 6 to 24 months, parts of the Northeast at most time scales, the Mid-Mississippi to Ohio Valleys at 1 to 3 months and 9 to 24 months, parts of the Great Lakes at all time scales, the Tennessee Valley to Gulf of Mexico coast at 9 to 24 months, and most of the Atlantic Coast at 24 months. An interesting pattern continues at the 24-month time scale — very dry conditions dominate across the West to western portions of the Plains, while very wet conditions dominate the Lower Mississippi Valley to Great Lakes and eastward.
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.
For the Northern Hemisphere, April is in the middle of climatological spring, which is the transition season from the time of year when evapotranspiration is minimal to when it is maximum. During April 2022, temperatures were much above normal in the southern tier states and much below normal in the northern tier states, especially west of the Mississippi River. Near- to cooler-than-normal temperatures dominated much of the CONUS for the last 2, 3, and 4 months, except along the East and West Coasts. This temperature anomaly pattern resulted in similar patterns of anomalies of similar magnitude for the SPEI and SPI for the last 9 months (SPEI maps for last 1, 2, 3, 4, 6, 9 months) (SPI maps for last 1, 2, 3, 4, 6, 9 months). The dryness in the West (especially California) for January-April was notable, but the temperatures were not.
Much of the West was extremely warm during 2021 and earlier years. This increased evapotranspiration and resulted in more extreme SPEI values than SPI values at the 1- to 6-year time scales (SPEI maps for last 12, 15, 18, 24, 30, 36, 48, 60, 72 months) (SPI maps for last 12, 15, 18, 24, 30, 36, 48, 60, 72 months).
California had the second most extreme 15-month SPEI and third most extreme 15-month SPI; Idaho had a record dry SPEI and top ten dry SPI at the 30-month time scale; and Oregon had a record dry SPEI and top ten dry SPI at the 30-month time scale.
Much of the West (from the Rockies to the West Coast) has been excessively warm for the last 10 to 30 years, with the last 12 months being the fourth warmest May-April on record. The region has also been persistently drier than the long-term average. When the heat and dryness are integrated over time, the West has had the second driest and third warmest 24-month May-April period, and second driest and sixth warmest 36-month May-April period.
April 2022 and March-April were drier than normal across Maui to Kauai, while the Big Island of Hawaii had a mixed precipitation anomaly pattern. Drier-than-normal conditions were widespread across the state at the 3- to 4-month time scales. A wet December 2021 resulted in mixed precipitation anomaly pattern at the 6-month time scale. At 7 to 12 months, there were still wetter-than-normal areas on the Big Island and Oahu, but drier-than-normal conditions dominated on Maui, Molokai, and Kauai. At longer time scales, a mixed anomaly pattern was evident with wetter-than-normal conditions dominating the further out in time (last 1, 2, 3, 4, 6, 7, 9, 10, 12, 24, 36, 48, 60 months) (climate engine model percent of normal precipitation map for the last month). Monthly streamflow was below normal at many streams on Oahu but near to below normal on the other islands. Drought and abnormal dryness contracted on all of the islands except Lanai and Kahoolawe. The overall drought footprint shrank from 78.7 percent last month to 47.1 percent on the May 3rd USDM map.
April 2022 and March-April 2022 were drier than normal across most of Alaska. At the 3- to 4-month time scales, northern portions of the state were drier than normal and southern portions wetter than normal. By 6 months, most of the state was wetter than normal except for the Aleutians to coastal Northwest Gulf, where drier-than-normal conditions were common. This pattern continued to longer time scales except for some dryness in some northern coastal areas (low elevation station precipitation anomaly maps for the last 1, 2, 3, 4, 6, 7, 9, 10, 12, 24, 36, 48, 60 months) (high elevation SNOTEL station precipitation percentile map for the last 1, 4, 7, and 12 months) (high elevation SNOTEL station precipitation anomaly maps for April 2022 and October 2021-April 2022) (SNOTEL basin precipitation anomaly map for October 2021-April 2022) (SNOTEL basin and station precipitation anomaly maps for the last 1, 4, 7, and 12 months) (climate division precipitation rank maps for the last 1, 3, 4, 6, and 12 months) (climate engine model percent of normal precipitation map for the last month) (Leaky Bucket model precipitation percentile map).
March temperatures were warmer than normal across the west coast and near to cooler than normal across the rest of the state. Warmer-than-normal temperatures expanded across the western and southern portions of Alaska at the 2- to 4-month time scales. At the 6- to 12-month time scales, near to cooler-than-normal temperatures dominated in most areas (low elevation station temperature anomaly maps for the last 1, 2, 3, 4, 7, 12 months) (climate division temperature rank maps for the last 1, 3, 4, 6, and 12 months) (gridded temperature percentile maps for the last 1, 3, and 4 months) (Leaky Bucket model temperature percentile map). End-of-April satellite-based and SNOTEL station and basin observations of snow water equivalent (SWE) in snowpack was mostly near to above normal with some below-normal locations. A large wildfire (the Kwethluk Fire) burned in the tundra of the Yukon Delta National Wildlife Refuge in southwest Alaska during April (wildfire maps for April 22, 25, 30). The Alaska Center for Climate Assessment and Policy reported that low elevations in much of lower Yukon-Kuksokwim region had a greater percentage than normal of cold season precip fall as rain rather than snow and lost the winter snowpack unusually early this spring (late March to early April). Since mid-March there has been hardly any precipitation and it's been warmer than normal, though not dramatically so. All of this combined to allow the Kwethluk wildfire to grow to about 7000 acres, which is the largest wildfire in Alaska during April in at least 30 years.
Modeled soil moisture and experimental satellite-based observations of soil moisture (GRACE root zone and surface soil moisture; 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) and groundwater showed drier-than-normal conditions in some areas, although the ground is likely still frozen across most of Alaska at this time of year. Monthly streamflow (for those streams that were not frozen) was mostly near to above normal with some below-normal streams in the Cook Inlet area. An area of abnormal dryness was introduced on the USDM map this month in southwest Alaska to reflect the dry and relatively warm spring.
Puerto Rico and U.S. Virgin Islands
April 2022 was drier than normal across most of Puerto Rico (PR) and the U.S. Virgin Islands (USVI). Dry conditions extended across much of the region at the 2-month time scale. But a wet February resulted in widespread above-normal precipitation at the 3- to 4-month time scales. The USVI and much of PR were drier than normal at the 6- to 48-month time scales, with a mixed anomaly pattern prevailing at 60 months (radar-based precipitation anomaly estimates for the last 1, 2, 3, 4, 6, 7, 12 months) (low elevation station precipitation maps for the last 1, 2, 3, 4, 6, 7, 9, 10, 12, 24, 36, 48, 60 months) (climate engine model percent of normal precipitation map for the last month: PR and USVI, Caribbean and Gulf of Mexico region).
Root zone analyses indicated that soil conditions were dry along the southern and northwestern coasts and some eastern interior regions of PR (root zone soil saturation fraction; relative soil moisture at 0-10 cm [0-4 in], 10-40 cm [4-16 in], 40-100 cm [16-39 in], 100-200 cm [39-79 in] depth). Monthly streamflow was below normal at many locations in PR. In the USVI, groundwater during April continued to decline on St. Thomas, St. John, and St. Croix. The groundwater level on St. Croix in April reached a new record low value compared to the 2016-2022 record. The April values at St. John and St. Thomas were very low but had not reached record low values based on the 2016-2022 period, although the St. John value was the lowest since 2017. Moderate drought shrank to cover 3.4 percent of PR on the May 3rd USDM map, while in the USVI, severe drought continued on St. Croix and moderate drought improved to abnormally dry conditions on St. Thomas and St. John.
CONUS State Precipitation Ranks
April 2022 was drier than normal across the Southwest to southern and central Plains, and in swaths from the Midwest to Southeast, with record-dry conditions occurring locally in the Four Corners states. Twelve states had a precipitation rank in the driest third of the 128-year historical record for April, including four in the top ten driest category — New Mexico (second driest), Kansas (third driest), Colorado (fifth driest), and Arizona (sixth driest).
February-April 2022 was drier than normal across most of the West and southern to central Plains, and along parts of the Gulf of Mexico and Atlantic coasts, with record-dry conditions occurring locally in parts of the West and Plains. Seventeen states had a precipitation rank in the driest third of the 1895-2022 historical record, including five in the top ten driest category — California (third driest), Utah (seventh driest), Nevada (eighth driest), Arizona (ninth driest), and New Mexico (tenth driest).
The year to date (January-April 2022) had a precipitation anomaly pattern that was similar to that of February-April, except the anomalies were more extreme in the Far West with record-dry conditions more widespread in California and Nevada. Sixteen states had a precipitation rank in the driest third of the historical record, including six in the top ten driest category — California (driest January-April on record), Utah and Nevada (each third driest), Arizona (sixth driest), and New Mexico and Nebraska (both tenth driest).
November 2021-April 2022 was drier than normal across most of the West and central to southern Plains, and along the Gulf of Mexico and Atlantic coasts, with record-dry conditions locally in the Plains. Twenty-seven states had a precipitation rank in the driest third of the historical record, including eleven in the top ten driest category —
- in the West: Nevada and Utah (each seventh driest), and California and New Mexico (each eighth driest);
- in the Plains and Lower Mississippi Valley: Nebraska (fourth driest), Kansas (fifth driest), Louisiana (seventh driest), and Texas (tenth driest);
- in the East: Delaware (eighth driest), and Maryland and New Jersey (both tenth driest).
The last 12 months (May 2021-April 2022) were drier than normal across much of the West and Plains, and parts of the Upper Mississippi Valley, Mid-Atlantic states, southern Florida, and extreme northern New England. Thirteen states had a precipitation rank in the driest third of the historical record. None were in the top ten driest category, but two were close — California (11th driest) and Montana (12th driest).
During April 2022, the Primary Hard Red Winter Wheat agricultural belt was drier and mostly warmer than average. The month ranked as the second driest and 47th warmest April, regionwide, in the 1895-2022 record. April 1989 was the driest April.
October marks the beginning of the growing season for the Primary Hard Red Winter Wheat belt. October 2021-April 2022 was warmer and mostly drier than normal. The period ranked as the sixth driest and tenth warmest October-April, regionwide, on record.
During April 2022, the Primary Corn and Soybean agricultural belt was mostly cooler than average with a mixed precipitation anomaly pattern. The month ranked as the 55th wettest and 26th coolest April, regionwide, in the 1895-2022 record.
March marks the beginning of the growing season for the Primary Corn and Soybean belt. March-April 2022 was mostly cooler than normal with a precipitation anomaly pattern that was drier in western portions and near to wetter than normal in eastern and southern portions. The period ranked as the 60th warmest and 43rd wettest March-April, regionwide, on record.
According to the U.S. Department of Agriculture (USDA), as of May 3, 2022, drought affected approximately 90 percent of sorghum production, 71 percent of barley production, 69 percent of winter wheat production, 64 percent of the sheep inventory, 56 percent of cotton production, 56 percent of the cattle inventory, 45 percent of the milk cow inventory, 41 percent of hay acreage, 39 percent of rice production, 35 percent of spring wheat production, 23 percent of corn production, and 14 percent of soybean production. Based on May 1 USDA statistics, 43 percent of the nation's winter wheat and 56 percent of the nation's pasture and rangeland were in poor to very poor condition, and 32 percent of the topsoil and 37 percent of the subsoil were short or very short of moisture (dry or very dry). According to the USDA, the U.S. national pasture and rangeland condition index is starting the 2022 pasture/rangeland season worse than any other year this century. For winter wheat condition, Texas led the pack with 77 percent of winter wheat in poor to very poor condition, followed by Colorado (57%), Oklahoma (51%), Montana (49%), Kansas (39%), and Nebraska (38%). Those states having more than 50 percent of the pasture and rangeland in poor to very poor condition included Arizona (89%), Montana (89%), Texas (74%), Nebraska (73%), South Dakota (58%), Wyoming (58%), New Mexico (56%), and Colorado (52%). States having more than 50 percent of the topsoil moisture short or very short included New Mexico (90%), Colorado (88%), Texas (81%), Wyoming (76%), Montana (73%), Kansas (68%), Oklahoma (63%), Nebraska (63%), and Georgia (55%). Those states having more than 50 percent of the subsoil moisture short or very short included New Mexico (93%), Wyoming (86%), Montana (84%), Colorado (82%), Texas (82%), Nebraska (78%), Kansas (68%), Oklahoma (65%), Oregon (52%), and South Dakota (51%).
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), April 2022 was drier-than-normal in the southern parts of the FSM and in American Samoa. It was near to wetter than normal across Palau, the Marianas, and most of the RMI and FSM.
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) in the northern RMI. April precipitation was above the monthly minimums at the rest of the stations across the USAPI. 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 April 2022, which is in the dry season for most locations in northern and western Micronesia. Precipitation was below the monthly minimum but above normal (1981-2010 normal), because the normals are low, at:
- Wotje: April 2022 precipitation 4.76 inches, April normal mean 3.51 inches
At some stations, the dry season is not as pronounced or, for Pago Pago and Kapingamarangi, this is the wet season, so the normal monthly precipitation is above the monthly minimum. Precipitation was above the monthly minimum but below normal at:
- Kapingamarangi: April 2022 precipitation 8.97 inches, April normal mean 12.12 inches, April normal median 13.64 inches
- Pago Pago: April 2022 precipitation 5.42 inches, April normal mean 11.02 inches, April normal median 9.39 inches
In the table below, the station identified as Koror is Palau International Airport (Airai).
As measured by percent of normal precipitation, Kapingamarangi and Pago Pago were drier than normal in the short term (April, the last 3 months [February-April 2022], and the year-to-date [January-April]) and long term (last 12 months [May 2021-April 2022]). Guam was drier than normal at the 3- and 4-month time scales but near to wetter than normal for April and the 12-month time scale. Chuuk was drier than normal for the year to date but wetter than normal at the other 3 time scales. Lukunor was slightly drier than normal at the 3- and 12-month time scales but near to wetter than normal for April and the year to date. Airai, Kosrae, Kwajalein, Majuro, Pohnpei, Saipan, and Yap were near to wetter than normal at all 4 time scales.
Based on percent of normal average (instead of normal median values), in the Marianas Islands, precipitation during April was above normal across the islands. Wetter-than-normal conditions dominated at the 2- to 12-month time scales. Drier-than-normal conditions dominated at the 24-month and longer time scales (percent of normal precipitation maps for the last 1, 2, 3, 4, 6, 7, 9, 10, 12, 24, 36, 48, 60 months).
Based on percent of normal average (instead of normal median values), in the Marshall Islands, precipitation during April was above normal at the regular-reporting stations. This anomaly pattern held for the 2- to 3-month time scales, with drier-than-normal conditions appearing at northern stations at the 4-month time scale and spreading to the southwest by 24 months. The anomaly pattern became mixed at longer time scales (percent of normal precipitation maps for the last 1, 2, 3, 4, 6, 7, 9, 10, 12, 24, 36, 48, 60 months).
According to the April 30th USDM produced for the USAPI, extreme drought improved to severe drought at Wotje, and drought and abnormal dryness ended in the FSM and Marianas. Wotje was the only station analyzed with drought while the rest of the USAPI stations were free of drought and abnormal dryness.
- Very wet ITCZ (Inter-Tropical Convergence Zone) trade-wind weather across southern and central RMI meandered northward at times, bringing beneficial rain to Wotje and other northern islands. The observer on Wotje reported at mid-April that water catchment tanks were 50% of capacity and vegetation was beginning to green up. Some islands have reverse osmosis units, but many were still inoperable. Conditions varied quite a bit island to island but an overall wetter pattern in recent weeks led to improved conditions. Residents continued to conserve water.
- By early May, the observer on Wotje reported water catchment tanks were still around 50% of capacity and vegetation continued to green up. Conditions varied quite a bit island to island but an overall wetter pattern in recent weeks led to improved conditions.
The abundant rainfall improved April precipitation ranks, but a couple were still in the top 5 and top 10 driest category:
- Kapingamarangi: fifth driest April (in a 30-year record), November-April, October-April, and September-April; third driest March-April, July-April, and June-April; and second driest May-April (in 17 years of data).
- Pago Pago: eighth driest April (57 years of data); third driest March-April; seventh driest September-April and July-April.
- Wotje: This is normally a dry time of year, so the 4.76 inches of rain that fell in April 2022 ranked the month as the eleventh wettest April in the 39-year record. But December 2021-April 2022 still ranked as the eighth driest December-April, and June-April and May-April ranked ninth driest.
At the wet end of the scale, Ulithi had the wettest April on record and Airai, Ailinglaplap, Mili, and Majuro ranked second wettest. Mili also had the wettest 12-month period (May-April) on record while Pohnpei and Woleai ranked second wettest.
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 April 2022, November 2021-April 2022 (last 6 months), and May 2021-April 2022 (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||April 2022||Nov 2021-Apr 2022||May 2021-Apr 2022||Period of Record|
NOAA Regional Climate Centers
More information, provided by the NOAA Regional Climate Centers and others, can be found below.
As noted by the Southeast Regional Climate Center, temperatures were near average across much of the Southeast region for the month of April while precipitation was variable with only a few wet and dry extremes reported. The driest locations were found across southern Florida, southern Georgia, eastern North Carolina, and Virginia.
Drought conditions changed very little across the Southeast region for April. Abnormally dry conditions (D0) with pockets of moderate drought (D1) were observed across northern Virginia. A pocket of severe drought (D2) was in eastern North Carolina coast ringed by moderate drought (D1) and abnormally dry conditions (D0). Moderate drought (D1) ringed by abnormally dry conditions stretched from eastern South Carolina down into southern Georgia. In southern Florida, there were pockets of severe drought (D2), ringed by moderate drought (D1) and abnormally dry conditions (D0). Drought conditions remained the same across Puerto Rico for the month as well, with pockets of moderate drought (D1) ringed by an area of abnormally dry conditions (D0) in the southern part of the Island and pockets of moderate drought (D1) to severe drought (D2) across the Virgin Islands.
Due to the severe and moderate drought located in the citrus growing region of Florida, farmers had to run irrigation in all areas. The warm and dry conditions allowed for favorable planting conditions in the Panhandle. Moderate drought conditions in southern Georgia required farmers to run irrigation in fields. Cotton planting continued but was slowed due to a lack of soil moisture in some areas. Warm conditions with sporadic rainfall across much of South Carolina resulted in favorable planting conditions, although drought stress is anticipated if the dry conditions continue.
As explained by the Southern Regional Climate Center, temperatures were relatively warm toward the west and cool toward the east, and, like temperature, precipitation was relatively high toward the east and relatively low toward the west. Texas ranked 21st driest, with slightly more than half its normal rainfall, Oklahoma ranked 32nd driest, and Louisiana 48th driest. Overall, the region was 46th driest out of 128 years. Forty-six Texas stations recorded zero precipitation and 16 more recorded but a trace. Only four out of 27 stations in Texas's Trans Pecos climate division reported measurable precipitation.
Where drought conditions were mild, drought improved, but the worst drought got worse. On April 26, about 56% of the region was in drought, a drop of 12% from last month, and severe drought also declined from 52% to 46%. However, the proportion in at least extreme drought (D3) increased from 29% to 32% and the proportion in exceptional drought (D4) increased from 5% to 11%. Tennessee was drought-free, while Arkansas and Mississippi had 6% and 4% drought coverage, respectively. About 14% of Louisiana, 39% of Oklahoma, and 50% of Texas were in extreme or exceptional drought. The dry conditions made the establishment of a warm-season crop challenging or impossible in many of the affected areas, and winter wheat remained mostly in very poor condition. The wildfire risk remained high in western Texas and Oklahoma, but the typical reduction of wind speeds from April's peak was expected to reduce the likelihood of large wildfires.
As described by the Midwest Regional Climate Center, the average temperature for the Midwest was 44.4 degrees F (6.9 degrees C) for April, which was 4.3 degrees F (2.4 degrees C) below the 1991-2020 normal, and the average Midwest precipitation for April was 3.83 inches (97 mm), which was 0.16 inch (4 mm) above normal, or 104 percent of normal. Conditions were persistently wet across the Midwest, even in locations with below-normal precipitation. Drought conditions improved throughout April, with about 2% of the region in drought and 10% showing abnormal dryness by the month's end. Drought was confined to western Iowa while isolated pockets of abnormal dryness were reported across the upper Midwest and extreme eastern Kentucky.
As explained by the Northeast Regional Climate Center, April was wetter than normal for many areas, while the Northeast's April average temperature of 45.8 degrees F was 0.3 degrees F colder than normal. April precipitation for the 12 Northeast states ranged from 79 percent of normal in Rhode Island to 138 percent of normal in New Jersey, with nine states being wetter than normal.
The USDM from April 5 showed 1 percent of the Northeast in severe drought, 3 percent in moderate drought, and 29 percent as abnormally dry. In fact, 10 of the 12 Northeast states had drought or abnormal dryness present at the beginning of the month. Timely precipitation, particularly during the first half of April, helped alleviate some of the dry conditions. Severe drought eased in western Maine, while moderate drought eased in New Jersey, Pennsylvania, and much of Maryland and West Virginia. Abnormal dryness contracted across the region. The USDM from April 26 showed 1 percent of the Northeast in moderate drought and 17 percent as abnormally dry.
As summarized by the High Plains Regional Climate Center, April was the 'tale of two cities' in the High Plains. Grand Forks, North Dakota was among the wettest and coldest on record, while Colorado Springs, Colorado was among the warmest and driest on record. The northern states experienced well below-normal temperatures and multiple blizzards, while the southern states remained dry and dealt with wildfires. Several locations in North Dakota were among the wettest on record, in contrast to multiple places in the southern portions ranking among the driest. The above-normal precipitation in North Dakota helped improve drought conditions, while the dryness in the south only exacerbated drought conditions. In Colorado, Akron and Colorado Springs both observed their driest month on record with minimal precipitation falling. Several locations with eastern Wyoming, western Kansas, and western Nebraska also ranked among the driest Aprils on record.
Dryness continued in the southern parts of the region, while the northern parts received normal to above-normal precipitation. Drought conditions improved significantly in North Dakota and parts of South Dakota after the recent snowstorms, while Kansas and Nebraska remained dry. The dryness across the western parts of both Nebraska and Kansas led to widespread expansion of extreme drought (D3). Nearly 20 percent of both states are in D3 at the end of April. Some precipitation fell in the drought-stricken areas towards the end of the month, which should improve conditions. Severe drought (D2) also greatly expanded across eastern Colorado towards the end of the month, with many areas receiving well below 25 percent of their normal precipitation. Contrary to the dryness, the northern parts of the region have observed above-normal precipitation. Drought conditions improved one to two classes across the western Dakotas and northern Wyoming. Elsewhere in the region, other improvements and degradation were observed.
Wildfires were an issue in the southern portion of the region, particularly in Nebraska. Two large fires broke out during the month, which led to two deaths and several towns to be evacuated. The first fire broke out near Arapahoe, with nearly 35,000 acres burned over several days. Later in the month, another fire broke out nearby which burned over 44,000 acres. Several other fires occurred in Colorado during the month, particularly in areas that were extremely dry this month. Another interesting impact of the ongoing drought was the reduction of hunting permits available for pronghorn and mule deer in Wyoming. Due to the dryness, food sources of these animals are impacted. As a result, permits were reduced to conserve populations this year. Animal populations were already low from the previous year, with the mule deer population only 61 percent of the statewide goal.
As described by the Western Regional Climate Center, throughout the northern tier of the West, April brought a welcome return of the Pacific storm track and active weather that positively contributed to snow pack and water resources with colder-than-normal temperatures. Unfortunately, the active weather quickly ceased to the south, roughly along the 42 N parallel leading to drier-than-normal and hotter-than-normal conditions that drove worsening drought in the southern tier of the West and promoted extreme wildfire growth and behavior in Arizona and New Mexico. Numerous stations in southeastern California, southern Nevada, southern Utah, and throughout Arizona and New Mexico observed their driest April on record. Many stations recorded no precipitation for the month, including Las Vegas, NV (0.2 inch below average, 86 years of records), Bishop, CA (0.2 inch below average, 78 years of records), Phoenix, AZ (0.2 inch below average, 127 years of records), and Albuquerque, NM (0.5 inch below average, 131 years of records).
April precipitation improved widespread snow drought conditions throughout the northern Western U.S. mountains, but with an important caveat (see below). At the beginning of the month, when the state of the snow pack informs many important water resources decisions, snow pack was at or below average throughout much of the West, with conditions closer to normal in the Washington Cascades, Northern Rockies, and Colorado Rockies. The Oregon Cascades, Sierra Nevada of California, Basin and Ranges of Nevada and Utah, and ranges in the Snake River Watershed were all well-below normal. However, by the end of April, many regions in the northern tier, such as the Cascades and Northern Rockies, as well as the Sierra Nevada, gained 5-10 inches of liquid, providing a welcome late-season boost to snow packs that had begun to melt ahead of schedule following a generally warm, dry, and sunny winter and early spring. Despite these gains, as of this writing, approximately 95% of the western U.S. was in drought, with nearly a third (31%) experiencing extreme to exceptional drought. Dry fuels amidst prolonged drought and unfavorable fire weather (hot, dry, and windy) created conditions conducive for wildfire ignition and spread. Several large fires ignited in both Arizona and New Mexico, burning over 200,000 acres, destroying property, and prompting evacuations of numerous communities in both states.
Major snow pack gains in northern tier of West, but not enough to turn the tide of drought: Despite the 5-10 inches of liquid water gains in snow pack through the month of April, peak snow pack values remained below to well-below average for many locations. This highlights a limitation of the use of percent of average. During spring, when snow pack is melting, relatively small gains (or slowing of melt) can drive percent of average values up to exceed 100% of normal but obscuring the fact that peak snow pack was near, or in many cases, well-below average. April storms did bring locations throughout the northern tier of the West to their water year peak with active weather moderating melt rates and prolonging the winter season via precipitation and by limiting solar radiation and hot temperatures. Nonetheless, expectations of drought conditions remain, especially in the southern tier of the West, but throughout the region, due to below-average peak snow pack.
Sea surface temperatures (SST) north of the Hawaiian Islands were approximately 0 to 1 degree above normal. To the north, warming SSTs were emerging (recall 'the Blob') with colder SSTs persisting to the southeast of the islands as La Niña conditions develop and equatorial upwelling strengthens. Drought remained on all Hawaiian Islands, however some improvement has occurred throughout the winter with 68% of the Islands in some level of drought compared to 100% at the start of February. With a mean temperature of 78.2 degrees (2 degrees above average), Honolulu, HI experienced its fourth hottest April since records began in 1941. Dry conditions were observed on Maui, with Kahului measuring 0.09 inch of rainfall or 1.23 inches below average, marking its sixth driest April since 1905.
April was largely dry in Alaska, with Fairbanks observing its 10th driest April (0.02 inch of precipitation or 0.32 inch below average) since records began in 1930. Temperatures were warmer than normal in the west and colder than normal in the east. The anomalously deep snow pack that accumulated throughout the winter started to melt, producing minor runoff impacts. The annual cycle of river ice breakup commenced near the end of the month. Early snowmelt in southwest Alaska combined with dry conditions to allow pre-greened-up tundra to ignite, leading to Alaska's largest known April wildfire (approximately 10,000 acres) since monthly estimates began in 1993. Along the Panhandle, Juneau experienced within 0.01 inch of normal precipitation (3.44 inches observed; 3.45 inches average).