Issued 13 October 2022

September 2022 Palmer Z-Index
U.S. Percent Area Wet or Dry January 1996 - September 2022
September 2022 /monitoring-content/sotc/drought/2022/09/wa-p-reg045dv00elem01-07092022.gif

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

Detailed Drought Overview

A high pressure ridge dominated the atmospheric circulation over North America during September 2022. The ridge brought warmer-than-normal monthly temperatures to much of the CONUS, especially in the West, where record warmth occurred, and Great Plains. Pacific weather systems (upper-level shortwave troughs and closed lows) frequently penetrated the ridge. They weakened over the western CONUS as they moved through the ridge axis, but they regenerated east of the Rockies and manifested as a long-wave trough along the East Coast. The central CONUS was frequently dominated by a ridge or by a northwest flow. This pattern generally blocked Gulf of Mexico moisture from entering the CONUS and spread dry Canadian air into the Plains and eastward, resulting in a drier-than-normal month for much of the country. The migrating troughs brought above-normal precipitation to pockets in the West and central Plains, and contributed to a wetter-than-normal month in the Northeast. Above-normal precipitation was also spread into peripheral parts of the U.S. by tropical systems — Hurricane Kay brought rain to the Southwest (California, Nevada, and Arizona), Hurricane Fiona soaked Puerto Rico and the U.S. Virgin Islands before its powerful remnants spread rain over northern New England when it slammed into the Canadian Maritimes, Post-Tropical Cyclone Merbok clobbered western Alaska with rain and wind as part of a mid-latitude frontal system, and Major Hurricane Ian blasted the Florida peninsula with wind and flooding rain as the month ended. But drier air dominated nationwide, with the CONUS experiencing the tenth driest September in the 1895-2022 record. Cold fronts associated with the eastern trough brought a near- to cooler-than-normal month to the parts of the eastern CONUS. But warmer-than-normal air dominated nationwide, with the CONUS experiencing the fifth warmest September in the 128-year record.

The above-normal precipitation in the Northeast, Florida, Puerto Rico, the U.S. Virgin Islands, and parts of the Southwest to southern Plains contracted or reduced the intensity of drought or abnormal dryness in those areas. But hot and dry weather expanded or intensified drought or abnormal dryness in the Pacific Northwest, central and northern Plains to Mississippi Valley, and parts of the Great Lakes, Ohio and Tennessee Valleys, Gulf Coast, and Mid-Atlantic Coast. Drought expansion exceeded contraction with the USDM-based national moderate-to-exceptional drought footprint across the CONUS increasing from 45.5 percent at the end of August to 50.9 percent at the end of September (from 38.2 percent to 42.7 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 105 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 45.6 percent of the CONUS was in moderate to extreme drought at the end of September, which is more than the end of August. The percent area of the CONUS in moderate to extreme drought has hovered between roughly 35 and 53 percent for the last 25 months (since September 2020).

Numerous reports of drought impacts were received during September by the National Drought Mitigation Center. The impacts of the drought can be seen in several drought indicators, especially in the West, central and southern Plains to Mississippi Valley, and East Coast. These include:

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Drought conditions at the end of September, as depicted on the September 27, 2022 USDM map, included the following core drought and abnormally dry areas:

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.

September 2022 Palmer Z-Index
September 2022 PHDI

Used together, the Palmer Z Index and PHDI maps show that short-term drought occurred in Montana, the central to southern Plains to Mississippi River Valley, and Mid-Atlantic Coast, expanding or intensifying long-term drought (PHDI maps for September compared to August). Short-term drought also occurred in the Pacific Northwest, northern Plains, Great Lakes, and central Gulf of Mexico Coast, contracting long-term wet areas and intensifying areas with long-term drought. Short-term wet conditions occurred over much of the Northeast, the Florida peninsula, and parts of the Southwest, contracting or reducing the intensity of long-term drought.

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.

September 2022 SPI
August-September 2022 SPI
July-September 2022 SPI
April-September 2022 SPI

The SPI maps illustrate how moisture conditions have varied considerably through time and space over the last two years. Dryness is evident in the central Plains at all time scales, the southern Plains at all time scales except 2 and 3 months in Texas, and in the northern Plains at the 1- to 3-month and 24-month time scales. Parts to most of the Pacific Northwest are dry at the 1- to 3-month and 9- to 24-month time scales. Much of the Mississippi Valley is dry at 1 months and parts of it (especially the Mid-Mississippi Valley) are dry at 2 to 24 months. Parts of the Great Lakes to Ohio Valley are dry at 1, 2, 6, and 9 months. The Mid-Atlantic to southern New England Coasts are dry at the 2- to 12-month time scales. Much of the West is dry at 9 and 24 months, and parts are dry at 12 months. The wet conditions in the Southwest over the last 1 to 6 months are not enough to overcome the longer-term lack of precipitation. An interesting pattern continues at the 24-month time scale — very dry conditions dominate across the West to Great Plains, while very wet conditions dominate the central to eastern Gulf Coast, the Lower Mississippi Valley to Ohio Valley, and eastern Great Lakes to Northeast.

January-September 2022 SPI
October 2021-September 2022 SPI
October 2020-September 2022 SPI

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, September is at the beginning of climatological fall, which is the season when evapotranspiration is declining. During September 2022, however, temperatures were much above normal across most of the West to Great Plains, with record warm temperatures common in the West. During the last 3 months, record-hot temperatures were widespread across the West, and well-above-normal temperatures characterized the last 4 months across the West and Great Plains. The last 6 and 12 months had unusual warmth in the southern states, with some areas, especially in the southern Plains, record warm. Most of the CONUS was warmer than normal at 12 months. The excessive warmth increased evapotranspiration, especially in the West and Plains during the warm season, but even in the southern states during the cool half of the year. This temperature anomaly pattern resulted in more severe SPEI values than SPI values in the Pacific Northwest and Great Plains for the last 1 to 3 months, and in the Southwest to southern Plains at 6 to 12 months (SPEI maps for the last 1, 2, 3, 6, 9, 11, 12 months) (SPI maps for the last 1, 2, 3, 6, 9, 11, 12 months).

The heat gave record or near-record extreme SPEI values for California, Idaho, Oregon, and Washington during these time periods, while the corresponding SPI values were, in most cases, not record dry or only moderately dry:

Texas had the second warmest and ninth driest October 2021-September 2022 in the 1895-2022 record. And much of the West has been extremely warm during the last several years. This increased evapotranspiration and resulted in more extreme SPEI values than SPI values for Texas at the 1-year time scale and in the West at the 1- to 6-year time scales (SPEI maps for last 12, 18, 24, 36, 48, 60, 72 months) (SPI maps for last 12, 18, 24, 36, 48, 60, 72 months).

The heat gave near-record extreme SPEI values for California and Oregon during these time periods, while the corresponding SPI values were not as extreme:

Regional Discussion

Western United States

September precipitation was above normal across much of California and the Great Basin and parts of the Southwest and Rocky Mountains, but below-normal in the Pacific Northwest and parts of the Great Basin and Rocky Mountains to adjacent High Plains. This precipitation anomaly pattern extended to the last 2 to 3 months, with record dryness in coastal Washington. Earlier in the year, precipitation was above-normal in the Pacific Northwest and below normal in California to the Great Basin. For the year-to-date, the precipitation anomaly pattern evens out with some above-normal areas in the Pacific Northwest and Southwest, some below-normal areas in these two regions, and record dryness in California. Previous years have been very dry across the West, with below-normal precipitation anomalies dominating at longer time periods (low-elevation precipitation anomaly maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months) (high-elevation SNOTEL station precipitation percentile maps for the last 1, 3, 9, 12, 24, 36 months) (high-elevation SNOTEL station and basin precipitation anomaly maps for the last 1, 3, 9, 12, 24, 36 months) (climate division precipitation percentile maps for the last 1, 3, 6, 9, 12 months) (gridded precipitation percentile maps for the last 1, 3, 9 months).

Westwide, the mix of precipitation anomalies gave September 2022 a rank of 59th driest in the 1895-2022 record. But the widespread excessive warmth resulted in the warmest September, westwide, in the 128-year record. The persistent warmth during the summer gave the Western U.S. the warmest August-September and July-September. August-September 2022 ranked 30th wettest and July-September ranked 42nd wettest. The drier conditions earlier in the year gave the Western U.S. the 14th driest January-September, while temperatures were still warm westwide, ranking the year-to-date 13th warmest. November 2021 was dry but October 2021 was wet, so October 2021-September 2022 ranked as the 48th driest such 12-month period, and widespread warmth gave the region the sixth warmest such 12-month period. The Western U.S. has experienced a strong warming trend over the last 40 years. Persistently hot and dry conditions during previous years resulted in the seventh driest and fourth warmest October-September 24-month period, and third driest and fifth warmest October-September 36-month period.

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 for a sixth consecutive month, dropping to 57.2 percent at the end of September 2022.

Great Plains

Although precipitation anomalies varied across the Great Plains during the last 12 months, the central and southern Plains have generally seen persistently drier-than-normal conditions. Temperatures have been mostly hotter than normal, especially during the last six months. Regionwide, the Great Plains has had the following precipitation and temperature ranks during 2022:

Regionwide, the Great Plains has experienced unusually warm temperatures more often than not during the last 20 years. Summers during the last 20 years have frequently been nearly as dry and hot as the 1930s and 1950s drought years.

Hawaii

September 2022 was generally wetter than normal over the central Hawaiian Islands (Molokai to Maui) and drier than normal to the west and east. Drier-than-normal conditions dominated over the last 2 to 9 months. The precipitation anomaly pattern across the state was mixed at 12 to 48 months, with wetter-than-normal conditions dominating at 60 months (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 near to below normal on Kauai and Oahu but mostly below to much below normal on Maui and the Big Island. Vegetation was stressed on parts of all of the main islands, but especially on Molokai, Maui, Oahu, and leeward parts of the Big Island (satellite analyses of stressed vegetation, drought risk, VHI).

Drought or abnormal dryness contracted this month on the western islands and the lee side of the Big Island, but expanded on the windward side of the Big Island. The area of moderate to exceptional drought fell from 94.0 percent of the state at the end of August to 81.1 percent on the September 27th USDM map.

Alaska

September 2022 was wetter than normal across most of Alaska, with a few drier-than-normal areas in the south and along the northern coast. At the 2- to 4-month time scales, drier-than-normal conditions linger in the southern panhandle but become more evident in the eastern interior, with the eastern interior dryness reaching its greatest magnitude at 5 to 6 months. Wetter-than-normal conditions dominate at longer time periods (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, 5, and 12 months) (SNOTEL basin and station precipitation anomaly maps for the last 1, 5, and 12 months) (climate division precipitation rank maps for the last 1, 3, 6, 9, and 12 months) (climate engine model percent of normal precipitation map for the last month) (station percent of normal map for September from ACCAP) (Leaky Bucket model precipitation percentile map).

September temperatures were mostly warmer than normal. Some near to cooler-than-normal temperatures appeared in eastern areas at 2 to 3 months. Warmer-than-average temperatures dominated at longer time scales, when compared to the long-term (1926-2022) average. But when compared to more recent (1991-2020) normals, cooler-than-normal temperatures dominated because of a pronounced warming trend in recent decades (low elevation station temperature anomaly maps for the last 1, 2, 3, 4, 9, 12 months) (climate division temperature rank maps for the last 1, 3, 6, 9, and 12 months) (gridded temperature percentile maps for the last 1, 3, and 9 months) (Leaky Bucket model temperature percentile map).

Above-normal July-September precipitation helped restore soil moisture in most areas [modeled soil moisture; experimental satellite-based observations of soil moisture (SMOS; GRACE root zone and surface soil moisture; SPoRT relative percent of soil moisture for 0-10 cm [0-4 inches] depth, 10-40 cm [4-16 inches] depth, 40-100 cm [16-39 inches] depth, 100-200 cm [39-79 inches] depth) and groundwater]. Satellite observations of vegetative health (stressed vegetation, VHI, drought-related stress) showed improved vegetative conditions. Monthly streamflow was mostly near to above normal.

Only a small area of abnormal dryness lingered in the eastern interior region of Alaska on the September 27th USDM map.

Puerto Rico and U.S. Virgin Islands

Hurricane Fiona brought heavy flooding rains to Puerto Rico (PR) and the U.S. Virgin Islands (USVI) in mid-September. It caused massive devastation when it struck PR. The Fiona rains gave much of PR a September precipitation total in excess of 20 inches and ended drought and abnormal dryness across the island. The rains were not as heavy on the USVI, but were enough to improve drought conditions. Precipitation was above normal across PR and the USVI for the last 1 to 4 months, with some below-normal stations appearing in northern areas of both PR and the USVI at 6- to 9-month time scales. At the 12-month time scale, the USVI and northwest parts of PR along with a few other areas on the island had below-normal precipitation. Drier-than-normal conditions were more widespread 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 and Gulf of Mexico region).

Root zone analyses indicated that soil conditions were moist across the USVI and PR except maybe at the deepest layers (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). Satellite analyses showed the lack of vegetative stress due to drought (VHI for PR and USVI, drought risk for PR and USVI, stressed vegetation for PR and USVI). Monthly streamflow on PR was near to much above normal across the island. In the USVI, groundwater rose significantly on St. John, St. Thomas, and St. Croix due to September's rain. The end-of-September groundwater level on St. Thomas returned to pre-drought levels, while the groundwater levels on St. Croix and St. John were still at drought levels compared to recent (last 10 years) history.

Drought and abnormal dryness vanished from PR on the September 27th USDM map. In the USVI, at the end of September, drought and abnormal dryness ended on St. Thomas, extreme drought improved to abnormal dryness on St. John, and severe drought improved to moderate drought on St. Croix.

CONUS State Precipitation Ranks

September 2022 was drier than normal across the Great Plains to Mississippi Valley, Pacific Northwest, and Great Lakes to Mid-Atlantic and Gulf Coasts (except southern Florida). Twenty-three states had a precipitation rank in the driest third of the 128-year historical record for September, including five in the top ten driest category — Oklahoma (fifth driest); Louisiana (eighth driest); and Arkansas, Missouri, and South Dakota (each tenth driest). Washington almost made the top ten at eleventh driest.

July-September 2022 was drier than normal across the Great Plains to Mississippi Valley, in the Pacific Northwest, and Mid-Atlantic to southern New England Coasts. Record dryness occurred in parts of the Pacific Northwest and central Plains. Fourteen states had a precipitation rank in the driest third of the 1895-2022 historical record for July-September, including five in the top ten driest category — Washington (second driest), New Jersey (sixth driest), Oklahoma and Oregon (both seventh driest), and Kansas (eighth driest). Nebraska almost made the top ten at twelfth driest.

The last six months (April-September 2022) were drier than normal across most of the Great Plains; parts of the Great Basin to California; parts of the Great Lakes to Mississippi, Ohio, and Tennessee Valleys; and the Mid-Atlantic to southern New England Coasts. Ten states had a precipitation rank in the driest third of the historical record for April-September, including one in the top ten driest category — Nebraska (tenth driest) — and one that almost made it: Texas at eleventh driest.

The year-to-date (January-September 2022) was drier than normal across most of the Great Plains, California to the central Rockies, parts of the Upper Mississippi Valley to Great Lakes, and parts of the Southeast to southern New England. Record dryness occurred in California and locally in the central Plains. Nineteen states had a precipitation rank in the driest third of the historical record for January-September, including four in the top ten driest category — California (driest on record), Nebraska (sixth driest), Texas (eighth driest), and Nevada (tenth driest).

The last twelve months (October 2021-September 2022) were drier than normal across most of the Great Plains, the Great Basin to California, and the Southeast to New England. Record dryness occurred locally in the central Plains. Nineteen states had a precipitation rank in the driest third of the historical record for October-September, including three in the top ten driest category — Nebraska (eighth driest), and Texas and Delaware (both ninth driest) — and one that almost made it: New Jersey at 13th driest.

Agricultural Belts

During September 2022, the Primary Corn and Soybean agricultural belt was generally drier than normal in most areas, warmer than normal in the north and west, and cooler than normal in the south and east. The month ranked as the ninth driest and 40th warmest September, regionwide, in the 1895-2022 record.

March marks the beginning of the growing season for the Primary Corn and Soybean belt. March-September 2022 was generally drier than normal with near-normal temperatures in the north and west, and warmer than normal with a mixed precipitation anomaly pattern in the south and east. The period ranked as the 28th warmest and 43rd driest March-September, regionwide, on record.

During September 2022, the Spring Wheat agricultural belt was generally drier and warmer than normal. The month ranked as the 26th driest and second warmest September, regionwide, on record.

March marks the beginning of the growing season for the Spring Wheat belt. March-September 2022 was generally wetter than normal in the north and west to drier than normal in the southeast, with near-normal temperatures in the northeast, and warmer than normal everywhere else. The period ranked as the 25th warmest and 63rd driest March-September, regionwide, on record.

According to the U.S. Department of Agriculture (USDA), as of September 27, 2022, drought affected approximately 67 percent of barley production, 40 percent of corn production, 54 percent of cotton production, 65 percent of rice production, 73 percent of sorghum production, 38 percent of soybean production, 61 percent of spring wheat production, 64 percent of winter wheat production, 52 percent of hay acreage, 62 percent of the cattle inventory, 45 percent of the milk cow inventory, and 57 percent of the sheep inventory. Based on September 25 USDA statistics, 21 percent of the corn crop, 15 percent of the soybean crop, 42 percent of the cotton crop, and 43 percent of the nation's pasture and rangeland were in poor to very poor condition, and 54 percent of the nation's topsoil and 56 percent of the subsoil were short or very short of moisture (dry or very dry). According to the USDA, the national topsoil moisture rating of 54 percent is a high for the year-to-date and the third year in a row that it has peaked greater than 50 percent. The table below lists those states having 30 percent or more of topsoil or subsoil moisture short or very short, or 30 percent or more of the pasture and rangeland or corn, soybean, or cotton in poor or very poor condition:

Statewide topsoil moisture, subsoil moisture, pasture and rangeland condition, and crop condition

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), September 2022 was drier than normal in Palau, American Samoa, parts of the Marianas, western and southern RMI, and northern FSM. It was near to wetter than normal in other parts of the Marshalls, Marianas, 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) at Airai (Palau); Ulithi, Yap, Lukunor, and Kapingamarangi (FSM); Jaluit, Kwajalein, and Wotje (RMI); and Tutuila (American Samoa). September 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 September 2022, which is in 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:

  • Saipan: September 2022 precipitation 6.72 inches, September normal mean 10.21 inches, September normal median 10.09 inches

In the table below, the station identified as Koror is Palau International Airport (Airai).

Pacific Island Percent of 1981-2010 Normal Median Precipitation
Station Name Oct
2021
Nov
2021
Dec
2021
Jan
2022
Feb
2022
Mar
2022
Apr
2022
May
2022
Jun
2022
Jul
2022
Aug
2022
Sep
2022
Oct-
Sep
Chuuk138%112%149%39%39%166%138%176%68%107%70%121%107%
Guam NAS233%134%87%146%42%110%187%69%79%135%62%109%100%
Kapingamarangi30%29%148%94%131%58%66%10%25%61%51%44%53%
Koror233%70%155%113%124%156%303%203%81%72%119%45%119%
Kosrae129%122%160%74%77%216%195%132%139%169%117%134%118%
Kwajalein98%128%56%40%244%471%156%196%141%94%132%68%120%
Lukonor64%145%152%142%58%133%125%88%62%66%32%36%77%
Majuro119%130%77%61%128%298%255%66%71%96%74%159%120%
Pago Pago47%124%61%115%150%51%58%96%110%166%121%60%83%
Pohnpei95%174%96%76%182%211%157%112%122%173%138%143%134%
Saipan100%138%141%123%63%265%204%76%106%159%80%67%108%
Yap107%64%145%150%123%159%254%153%83%110%65%57%103%
Pacific Island Precipitation (Inches)
Station Name Oct
2021
Nov
2021
Dec
2021
Jan
2022
Feb
2022
Mar
2022
Apr
2022
May
2022
Jun
2022
Jul
2022
Aug
2022
Sep
2022
Oct-
Sep
Chuuk15.86"11.89"16.79"3.93"2.86"13.83"17.19"19.87"7.93"12.86"8.98"14.15"146.14"
Guam NAS26.68"9.87"4.47"5.84"1.28"2.28"4.74"2.35"4.88"13.71"9.15"13.74"98.99"
Kapingamarangi2.46"2.66"14.57"8.58"12.19"6.62"8.97"1.19"3.40"8.60"4.17"4.38"77.79"
Koror27.58"7.95"17.35"11.49"10.64"11.57"22.21"24.06"14.19"13.31"16.00"5.26"181.61"
Kosrae14.15"16.81"25.70"12.33"9.93"34.72"34.09"23.42"20.39"25.14"16.69"19.11"252.48"
Kwajalein10.97"14.47"3.74"1.25"6.45"11.07"8.21"13.17"9.78"9.23"12.81"7.34"108.49"
Lukonor7.25"13.20"17.10"11.94"5.16"12.28"14.14"10.27"7.19"10.52"4.55"3.70"117.3"
Majuro15.12"17.42"8.76"4.73"8.79"19.61"24.02"6.72"7.78"10.70"8.65"17.72"150.02"
Pago Pago4.38"12.58"7.83"15.39"17.94"5.50"5.42"9.32"5.84"9.23"6.53"3.92"103.88"
Pohnpei14.57"25.82"15.49"9.98"17.42"27.81"28.86"22.32"18.02"26.66"19.69"17.91"244.55"
Saipan10.63"7.76"5.41"3.12"1.62"5.01"5.36"1.81"3.84"14.16"10.55"6.72"75.99"
Yap13.00"5.68"12.31"9.57"6.36"7.23"14.28"12.04"10.04"16.54"9.57"7.76"124.38"
Pacific Island 1981-2010 Normal Median Precipitation (Inches)
Station Name Oct
2021
Nov
2021
Dec
2021
Jan
2022
Feb
2022
Mar
2022
Apr
2022
May
2022
Jun
2022
Jul
2022
Aug
2022
Sep
2022
Oct-
Sep
Chuuk11.51"10.61"11.25"10.10"7.25"8.32"12.47"11.30"11.66"11.98"12.86"11.71"136.77"
Guam NAS11.44"7.38"5.11"4.01"3.03"2.07"2.53"3.40"6.18"10.14"14.74"12.66"99.09"
Kapingamarangi8.19"9.27"9.84"9.15"9.27"11.43"13.64"12.08"13.78"14.15"8.13"9.93"145.85"
Koror11.84"11.39"11.16"10.18"8.56"7.44"7.32"11.83"17.48"18.53"13.50"11.77"152.90"
Kosrae10.94"13.83"16.11"16.67"12.93"16.06"17.51"17.75"14.64"14.91"14.22"14.22"213.87"
Kwajalein11.18"11.28"6.66"3.16"2.64"2.35"5.26"6.72"6.93"9.87"9.74"10.74"90.41"
Lukonor11.32"9.08"11.27"8.41"8.93"9.26"11.31"11.69"11.65"15.93"14.04"10.15"151.36"
Majuro12.73"13.44"11.39"7.74"6.88"6.58"9.42"10.11"11.01"11.17"11.69"11.17"125.25"
Pago Pago9.26"10.14"12.84"13.34"12.00"10.68"9.39"9.66"5.33"5.55"5.38"6.53"125.57"
Pohnpei15.27"14.83"16.08"13.18"9.55"13.17"18.41"19.96"14.81"15.43"14.26"12.55"182.36"
Saipan10.62"5.61"3.85"2.53"2.59"1.89"2.63"2.38"3.62"8.91"13.13"10.09"70.25"
Yap12.18"8.83"8.51"6.39"5.19"4.56"5.63"7.85"12.04"15.08"14.82"13.50"120.31"

As measured by percent of normal precipitation, Kapingamarangi and Lukunor were drier than normal in the short term (September and the last 3 months [July-September 2022]) and long term (year to date [January-September 2022] and last 12 months [October 2021-September 2022]). Pago Pago was drier than normal in the long-term and in September, and near normal for the last 3 months. Airai, Kwajalein, and Yap were drier than normal in the short-term and near to wetter than normal in the long-term. Chuuk and Guam were near to drier than normal for the last 3 and 9 months but near to wetter than normal for September and the last 12 months. Saipan was drier than normal for September but near to wetter than normal at the other 3 time scales. Kosrae, Majuro, and Pohnpei were near to wetter than normal in the short-term and long-term.

Based on percent of normal average (instead of normal median values), in the Marianas Islands, precipitation during September 2022 was below normal at most of the stations. It was mostly drier than normal at the 2- to 4-month and 9-month time scales, mostly wetter than normal at 12 months, with a mixed anomaly pattern at 6 months. Longer time scales were mostly drier than normal (percent of normal precipitation maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months).

Based on percent of normal average (instead of normal median values), in the Marshall Islands, September had a mixed precipitation anomaly pattern with drier-than-normal conditions in the north and southwest, and wetter-than-normal conditions at stations in between and in the southeast. The pattern was mixed for the last 2 to 4 months, with wetter-than-normal conditions dominating from 6 to 36 months and at the 60-month time scale. The pattern was mixed at 48 months (percent of normal precipitation maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months).

According to the September 30th USDM produced for the USAPI, moderate drought worsened to severe drought on Kapingamarangi, moderate drought began on Lukunor and Tutuila, and abnormal dryness began on Ulithi and Yap. The rest of the USAPI stations were free of drought and abnormal dryness.

The National Weather Service (NWS) office in Guam issued one Drought Information Statement (DGT) for drought in early October (on October 7) that noted that water levels for both private and public water tanks on Kapingamarangi were around 50% of capacity and crops were stressed from the recent dry weather. Eight 1,500 gallon water tanks were recently shipped to Kapingamarangi that will bolster water resources once they are installed. Other reports received by the NWS include:

  • Reduced water catchment levels were reported on Lukunor in late September.
  • In mid-September, reports were received from Ulithi of browning vegetation with most water catchments at a quarter to half full.
  • There has been a marked and gradual decrease of the Golden jellyfish numbers since October 2021 in Jellyfish Lake, which is located in the Koror State Rock Islands Southern Lagoon. The decline has been attributed to a rise in the lake's water temperature and lack of mixing of the lake's waters, and these conditions are brought about by La Niña conditions.
  • In American Samoa, reports from the local Atwater division indicate one of the water wells has dried out; information on conserving water for the territory is being distributed.

Satellite observations of vegetation health (VHI, stressed vegetation, drought stress) on Guam indicated a few parts of the island were still experiencing lingering stress, but most areas had no indication of drought.

September had a mix of wet and dry precipitation ranks across the USAPI. Record dryness was still occurring at Kapingamarangi and Lukunor, and had developed at Ulithi and Yap, at some time scales:

  • Kapingamarangi: 10th driest September (in a 31-year record), but driest April-September, March-September, February-September, and January-September; 2nd driest rank for all other longer time periods (December-September through October-September).
  • Lukunor: 2nd driest September (39 years) and driest August-September, July-September, June-September, and May-September.
  • Ulithi: 6th driest September (39 years), but driest August-September and July-September, and 2nd driest June-September.
  • Yap: 5th driest September (72 years), but driest August-September.
  • Jaluit: 7th driest September (39 years).
  • Guam: 8th driest August-September (66 years).
  • Pago Pago: 14th driest September (57 years of data), but 8th driest December-September.

At the wet end of the scale, Mili had the fourth wettest September and wettest July-September & April-September through October-September. Ailinglaplap had the wettest March-September (38 years), November-September, and October-September.

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 September 2022, April-September 2022 (last 6 months), and October 2021-September 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.

September 2022 USAPI Precipitation Ranks (1 = driest)
StationSeptember 2022Apr-Sep 2022Oct 2021-Sep 2022Period of Record
RankYearsRankYearsRankYears
Ailinglaplap3439373836361981-2022
Airai572557067701951-2022
Chuuk4372417141711951-2022
Fananu--6--2--22003-2022
Guam3066176635651957-2022
Jaluit73983819361981-2022
Kapingamarangi10311232211962-2022
Kosrae4351404328341954-2022
Kwajalein1171497050701952-2022
Lukunor2393266251981-2022
Majuro6069456854681954-2022
Mili3538373734341981-2022
Nukuoro3340323824371981-2022
Pago Pago1457155710561966-2022
Pingelap1939303728341981-2022
Pohnpei5572677169711951-2022
Saipan342284223331981-2022
Ulithi639193727331981-2022
Utirik--16--8--31985-2020
Woleai2741313328291968-2022
Wotje1639333825351981-2022
Yap572367133711951-2022
Map of USAPISeptember 2022 Precipitation (Inches)
Map of USAPI September 2022 Percent of Normal Precipitation
Map of USAPI July 2022-September 2022 Percent of Normal Precipitation
Map of USAPI January-September 2022 Percent of Normal Precipitation
Map of USAPI October 2021-September 2022 Percent of Normal Precipitation

SPI values for seven time periods for Pacific Islands, computed by the Honolulu NWS office.

SPI values for seven time periods for Pacific Islands

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, monthly temperatures were near average to slightly below average across much of the Southeast region in September, and monthly precipitation totals were highly variable owing to the occurrence of multiple hurricanes. The wettest locations were found across the Florida Peninsula and Puerto Rico, where monthly totals were as much as 20 inches (508 mm) above normal in places. In Puerto Rico, most of this precipitation was associated with Hurricane Fiona, which dropped between 10 and 30 inches (254 and 762 mm) of precipitation across the southern tier of the island. Hurricane Ian dropped 10 to 15 inches (254 to 381 mm) of precipitation across the Florida Peninsula from Fort Myers to Daytona Beach. Elsewhere across the region, precipitation was mostly below normal in September. The driest locations were found across parts of Alabama, Georgia, and northwest Florida, where monthly totals ranged from 1 to 3 inches (25 to 76 mm), with some locations recording less than 1 inch (25 mm) of precipitation (less than 25 percent of normal). After a wet August, Mobile, AL recorded only 1.22 inches (31 mm) of precipitation in September, which was over 4 inches (102 mm) below normal. Monthly precipitation was also below normal across much of Virginia, as the precipitation from Hurricane Ian did not reach the state until October 1st.

Drought coverage expanded across the Southeast in September due to the dry conditions, particularly across parts of Alabama, Georgia, northern Florida, and the eastern half of North Carolina and Virginia. The percent area of the region under abnormally dry (D0) conditions increased from 13 percent at the beginning of the month to over 33 percent by the end of the month, while the area under moderate drought (D1) increased slightly across eastern sections of North Carolina and Virginia. Additionally, a small area of severe drought (D2) emerged along the tip of the Delmarva Peninsula. In contrast, drought conditions were largely eliminated across southeast Florida and Puerto Rico due to Hurricane Ian and Hurricane Fiona, respectively. Drought conditions also improved across parts of the U.S. Virgin Islands.

South

As explained by the Southern Regional Climate Center, September 2022 was generally warm across the Southern region, with an average temperature of 76.6 degrees Fahrenheit. That value was 4.2 degrees below the all-time record, set in 2019, and 1.6 degrees above the 20th century average. Precipitation across the Southern region averaged less than 50 percent of normal for September. Driest was Oklahoma, which received an average of 0.72 inch, 22 percent of normal, making it the fifth driest September on record. Arkansas was tenth driest on record at 33 percent of normal, Louisiana was ninth driest at 39 percent of normal, and Mississippi was 15th driest on record at 41 percent of normal. Tennessee, at 70 percent of normal, ranked 42nd all-time. A total of nine stations in Arkansas, seven in Texas, and two in Oklahoma failed to receive measurable precipitation during the entire month. As a result, drought intensified throughout the Southern region. Oklahoma was driest, while Arkansas experienced the most rapid degradation of conditions.

The main story for the Southern region was drought. From September 6 to October 4, most of Arkansas and Louisiana experienced drought degradation, according to the USDM. About half of Tennessee, Mississippi, and Oklahoma were degraded, along with about a third of Texas. Net improvements were limited to northeastern Mississippi and parts of Texas. Most of the degradations took place during the latter half of the month, as what started out as a decently wet September transitioned to a dry one. As measured by the Drought Severity and Coverage Index (DSCI), Arkansas experienced on average more than a 1-category degradation, from 119 to 242, meaning that average drought conditions are now between D1 and D2 in Arkansas. Louisiana also degraded rapidly, from 1 to 97, meaning that typical conditions in Louisiana are now abnormally dry. Mississippi and Tennessee have similar drought status to Louisiana. Oklahoma is now at a DSCI of 393, meaning that extreme drought is the norm for that state as of now. Primary impacts across Oklahoma, Arkansas, and Texas include lack of forage growth, failure or reduced yield of maturing crops, lack of water for cattle in some cases, and increased risk of wildfire.

Midwest

As described by the Midwest Regional Climate Center, the average temperature for September in the Midwest was 64.4 degrees F (18 degrees C), which was 0.8 degrees F (0.5 degrees C) above the 1991-2020 normal, and September was drier than normal across the region. Midwestern precipitation totaled 2.26 inches (57 mm), which was 1.16 inches (29 mm) below normal, or 66 percent of normal. Preliminary estimates rank September 2022 as the 16th driest since 1895 for the region.

Drought or abnormal dryness affected nearly 47 percent of the Midwest by late September, an 18 percent expansion compared to the start of the month. While patchy dryness was distributed across the region, drought conditions were most widespread west of the Mississippi River. Drought intensification was most notable during September in Missouri. By month's end, drought covered over 56 percent of Missouri, and the most intense classification of drought (D4-Exceptional Drought) was introduced in several southwestern counties for the first time since 2012.

Corn and soybeans were reaching maturity near or slightly behind the 5-year pace for most of the region, except for Illinois and Indiana where corn was 14-19 percent behind the 5-year average and in Minnesota where soybeans were 13 percent behind. In Missouri and Iowa, pasture and range conditions were rated poor to very poor on about 35 percent of land, which was the most severe across the region.

Northeast

As summarized by the Northeast Regional Climate Center, September was warmer and wetter than normal for many parts of the Northeast, helping alleviate drought and dryness in the region.

The USDM released on September 1 showed 2 percent of the Northeast in extreme drought, 9 percent in severe drought, 13 percent in moderate drought, and 35 percent as abnormally dry. Many drought-stricken areas of the Northeast saw near- or above-normal precipitation in September, helping to ease drought and abnormally dry conditions. Extreme drought in southern New England contracted to encompass only northeastern Massachusetts. Severe drought eased in northern New England and shrank in coverage in southern New England, southeastern New York, and New Jersey. Moderate drought and abnormal dryness also contracted in New England, New York, and Pennsylvania. However, New Jersey, Delaware, and Maryland saw a mix of degradation and improvement. The USDM released on September 29 showed less than 1 percent of the Northeast in extreme drought, 4 percent in severe drought, 9 percent in moderate drought, and 18 percent as abnormally dry.

There were a multitude of impacts from the drought conditions. Several waterways in areas such as northeastern Massachusetts, Long Island, and parts of New Jersey observed record or near-record low streamflows. Below-normal groundwater levels were also found in multiple locations, raising concerns of rotting wood pilings that hold up some buildings in Boston, Massachusetts. Between January 1 and September 15, 94 wells had run dry in Maine. Water restrictions continued in numerous communities in New England and several in New York, Pennsylvania, and New Jersey. As of September 15, 106 New Hampshire water systems and seven municipalities had water restrictions in place, with most being mandatory. Despite rainfall during the first half of September adding nine inches to the water level, Connecticut Water's Killingworth reservoir remained seven feet below the spillway. For other reservoirs in the state, rainfall generally helped maintain water levels rather than provide significant increases. While some New Jersey reservoirs saw increased water levels, the Wanaque Reservoir was at less than 50 percent capacity as of late September. A few Massachusetts towns were under boil water advisories due to E. coli being detected in the drinking water, with drought conditions followed by heavy rain being a possible cause. Some residents of Portsmouth, Rhode Island, noted a change in the drinking water's smell and taste, with drought conditions thought to be one of the causes. Low water levels at Beltzville State Park in northeastern Pennsylvania caused the swimming area to close early for the season. Low water levels along Lake Waramaug in Connecticut brought concerns of increased shoreline erosion due to boat wakes. Similarly, boaters on Candlewood Lake in Connecticut were warned of low water levels as more water could not be pumped into the lake due to low water levels on the Housatonic River.

There was an increase in the number of Maine farmers who sought assistance for replacing or installing irrigation systems, driven by the state having its third consecutive summer with drought conditions. Dry weather brought an early end to the sunflower season at a farm in central Pennsylvania. With drought reducing hay yields, some cattle were already being fed supplemental hay, with some growers anticipating increased costs due to the need to buy more feed for winter. Hot, dry conditions in Delaware led to reduced soybean yields and losses of corn or an early corn harvest in non-irrigated fields. Some growers in southern New England noted that the September rainfall came too late to benefit crops such as corn and, in some locations, was too heavy to soak into the hardened soil. In addition, some corn mazes will be shorter in places such as Connecticut and New York due to stunted corn crops. Some growers in the Northeast reported smaller but sweeter apples and fewer or smaller-sized pumpkins. To keep crops growing, a Massachusetts farmer reported his irrigation costs were more than 10 times normal while another Massachusetts farmer was paying $3,000 a day to water his apple crop. Between reduced yields and increased costs to farmers, prices of popular fall crops such as apples and pumpkins have increased in some areas. Some growers in northern New England also reported Christmas tree losses.

Power companies in New Hampshire and Connecticut warned that drought-stressed trees could fall more easily, leading to an increased number of power outages. In New York, drought conditions in Ulster County helped fuel a wildfire that consumed around 14 acres, while an increased fire risk caused a Putnam County community to cancel Labor Day fireworks. A ban on open flame and charcoal fires was in effect in Massachusetts state parks. Drought conditions in Massachusetts contributed to more issues with rodents and bats but limited the mosquito population, reducing the number of mosquito-borne viruses.

High Plains

As summarized by the High Plains Regional Climate Center, the first month of meteorological fall was disappointing for much of the region. Instead of bringing cooler temperatures and much-needed moisture, the trend of warm and dry conditions, unfortunately, dominated the region. September temperatures were well above-normal across the region, with numerous locations ranking in the top 10 warmest months on record. The dryness that had been limited to Kansas and Nebraska spread into the Dakotas. Drought conditions rapidly spread across North Dakota in response to minimal precipitation.

Much of the High Plains was dry in September, with the majority of the Dakotas receiving less than an inch of precipitation. Drought-stricken areas in the western parts of Kansas and Nebraska received some precipitation, but not nearly enough to improve drought conditions. After observing near-normal to above-normal precipitation for much of this year, North Dakota was nearly bone-dry in September. Dickinson observed their driest September on record, with a paltry 0.07 inch (1.78 mm) of precipitation. In South Dakota, Sisseton fared slightly better with 0.08 inch (2.03 mm) to rank 2nd driest. Aberdeen and Pierre recorded less than 0.15 inch (3.81 mm) in September to rank in the top 10 driest. Looking further back, many locations in Kansas and Nebraska currently rank in the top 10 driest year-to-date. Arguably the driest place in the region is Garden City, Kansas. Only 5.01 inches (12.73 cm) of precipitation has fallen this year, nearly 2 inches (5.08 cm) below the previous record. In southwestern Nebraska, several locations are in the midst of their driest year-to-date. Most notably is Ogallala, which is the site of Lake McConaughy. Through the end of September, only a meager 5.74 inches (14.58 cm) of precipitation has been observed, well below the normal of 17.29 inches (43.92 cm).

Drought not only re-appeared, but rapidly spread across North Dakota after a very dry month. Outside of areas in Colorado and Wyoming, there were minimal improvements. Overall, there was a 16 percent increase in moderate to exceptional (D1-D4) this September. At the beginning of September, less than 1 percent of North Dakota was under drought conditions. By the end of the month, 72 percent of the state was experiencing drought. The lack of precipitation in the state in the past 60 days prompted the rapid expansion. Western Kansas has been the epicenter of the drought for most of the year for the state, but the southern part of the state has rapidly deteriorated in recent months. Currently, 25 percent of the state is in exceptional drought (D4). Elsewhere in the region, other improvements and degradation were observed.

Among the more interesting impacts of the drought this year occurred outside of Hays, Kansas. The nearby Ellis City Lake declared a public fish salvage in response to the extremely low water levels. With levels dangerously low, the fish are in danger of using oxygen too quickly. All catch limits and size rules on fish within the lake are removed, with any means of catch acceptable. The state of Kansas fears all the fish will die, resulting in them having to completely restart the aquatic population. The dire situation in southeastern Kansas led to serious consequences for one town. The town of Caney declared a water emergency in mid-September in response to low well levels. Water usage for outdoor purposes is banned, with the potential for citations or disconnections for residents. This part of Kansas rapidly dried out in the summer months, with September offering no relief.

West

As summarized by the Western Regional Climate Center, September 2022 brought a wild range of weather and climate extremes to the western U.S. An exceptional heatwave shattered many all-time temperature records in California but the month also brought widespread record mean temperatures throughout the West with numerous stations experiencing a top 5 hottest September. Dry conditions persisted in northwestern Washington while extreme rainfall occurred in multiple locations throughout California and western Nevada associated with an early season cold front and weak atmospheric river followed by post-frontal thunderstorms. Far southern California received heavy rainfall from Hurricane Kay as well as strong winds. Much of the interior western U.S. was near-normal precipitation-wise, with drier-than-normal conditions in northeastern Montana, southeastern Oregon and eastern New Mexico.

Precipitation was well-above normal across much of California, western and southern Nevada, and western Arizona. Reno, Nevada observed 0.52 inch (13 millimeters) for the month (230 percent of normal) for the third wettest September on record. Santa Maria, California observed its second wettest September in 112 years with 1.84 inches (46 millimeters) making for 4,500 percent of normal. The Pacific Northwest saw below-normal precipitation with the greatest negative anomalies in northwestern Washington and western, central, and southeastern Oregon at less than 25 percent of normal. Monroe, Washington recorded just 0.2 inch (5 millimeters) yielding eight percent of normal making for the driest September on record in 89 years. Dry conditions also occurred in eastern New Mexico. Clayton, New Mexico recorded 0.08 inch (2 millimeters) of rainfall for its fourth driest September (5% of normal) in 112 years of records.

According to the USDM in late September, 96 percent of the West was in drought with almost 20 percent of the West in extreme (D3) or exceptional (D4) drought. Drought reductions of up to two categories were found in New Mexico, central Montana, and parts of eastern Arizona. Drought expansion of up to two categories occurred in northwestern Oregon, Idaho, Washington and Montana. Far eastern Montana underwent a three-category expansion. Overall drought coverage across the West remains similar, but less severe, than one year ago.

Drought conditions remain widespread across the Hawaiian Islands, following warm and dry conditions. The USDM has 97 percent of the state experiencing abnormally dry to exceptional drought conditions. Roughly 47 percent of Hawaii is in severe drought.

Additional Resources


Citing This Report

NOAA National Centers for Environmental Information, Monthly Drought Report for September 2022, published online October 2022, retrieved on February 23, 2024 from https://www.ncei.noaa.gov/access/monitoring/monthly-report/drought/202209.