Issued 13 May 2024

April 2024 Palmer Z-Index
U.S. Percent Area Wet or Dry January 1996 - April 2024
April 2024 /monitoring-content/sotc/drought/2024/04/reg206dv00elem01-05042024.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

The upper-level atmospheric circulation over North America during April 2024 was very active with several short-wave troughs and closed lows migrating through the jet stream flow. Highly-amplified short-wave ridges were formed between the consecutive lows and troughs. This created a meridional pattern that propagated eastward with the migrating short-wave systems and which changed its shape as the systems evolved. Warmer-than-normal temperatures accompanied the ridges and cooler-than-normal temperatures followed behind cold fronts that were associated with the troughs and closed lows. When averaged over the month, the upper-level circulation was fairly zonal. The long-term average pattern consists of a ridge over the West and a trough over the East. April 2024 departed from the long-term average, with positive height anomalies reflecting the dominance of ridging in the broadscale flow and resulting in warmer-than-normal monthly temperatures across most of the CONUS.

Nevertheless, the troughs and closed lows, and their associated cold fronts and surface lows, put up a valiant fight. They eked out a cooler-than-normal month over the Florida peninsula and parts of the West. But they also brought above-normal precipitation and rounds of severe weather, especially east of the Rockies. April ended up wetter than normal over much of the northern Plains to Midwest and Northeast, parts of the southern Plains to Lower Mississippi Valley, and a few areas in the Southeast and Southwest. It was also wetter than normal across much of Puerto Rico and the U.S. Virgin Islands and part of Hawaii. The month was drier than normal over much of the West, large parts of the Great Plains, from the Tennessee Valley to Mid-Atlantic coast, and over parts of the Southeast, as well as much of Alaska.

The above-normal precipitation in the northern Plains to Midwest, and in parts of the West, Hawaii, and Puerto Rico, contracted or reduced the intensity of drought and abnormal dryness compared to the end of March. But dry conditions in parts of the Pacific Northwest, central and southern Plains, and Southeast resulted in expansion or intensification of drought and abnormal dryness. Drought contraction exceeded expansion with the USDM-based national moderate-to-exceptional drought footprint across the CONUS decreasing from 18.0% at the end of March to 17.0% at the end of April (from 15.1% to 14.2% for the 50 states and Puerto Rico).

According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 18.4% of the CONUS was in moderate to extreme drought at the end of April, which is about the same as the end of March (based on revised March values).

Drought conditions at the end of March, as depicted on the April 30, 2024 USDM map, included the following core drought and abnormally dry areas:

April 2024 /monitoring-content/sotc/drought/2024/04/20240430_usdm.png

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.

April 2024 Palmer Z-Index
April 2024 PHDI

Used together, the Palmer Z Index and PHDI maps show that short-term drought occurred in the central Plains, western parts of the Great Plains to Rocky Mountains, the Mid-Atlantic coast, and parts of the Southeast and Pacific Northwest, expanding or intensifying long-term drought and shrinking or reducing the intensity of long-term wet conditions (PHDI maps for April compared to March). Short-term wet conditions occurred across much of the Midwest and Mississippi Valley, and in parts of the northern Great Plains, contracting or reducing the intensity of long-term drought and expanding or intensifying 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.

April 2024 SPI
March-April 2024 SPI
February-April 2024 SPI
November 2023-April 2024 SPI

The SPI maps illustrate how moisture conditions have varied considerably through time and space over the last two years. Dryness is evident in parts of the Mid-Atlantic coast at 1-, 3-, and 24-month time scales. Parts of the Florida peninsula are dry at 1 to 3 months. Dry conditions are evident at the confluence of the Mississippi and Ohio Rivers at 2 to 6 and 24 months, with the dry area expanding along the Ohio and Lower Mississippi Rivers at 9-12 months. Parts of the central Plains (especially Kansas) are dry at 1-3 months and 24 months. Parts of the Pacific Northwest have dry conditions at all time scales, but especially 1-3 and 12-24 months. The central to southern Rockies have dryness at the 1- and 12-month time scales, with dry conditions along the Rio Grande River at all time scales except 6 months. The Upper Midwest is wet at short time scales but dryness is still evident at 12- to 24-month time scales. Wet conditions dominate from eastern parts of the Great Plains to the Northeast at 1-2 months, in parts of the Great Plains at 3-12 months, in parts of the Midwest at 3-9 months, across most of the Northeast at 2-24 months, and from California to the central Rockies at 3- to 24-month time scales.

August 2023-April 2024 SPI
May 2023-April 2024 SPI
May 2022-April 2024 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, April is in the middle of climatological spring, which is the season when days get longer, sun angle increases, and temperatures and evapotranspiration increase. During April 2024, temperatures were warmer than normal across much of the CONUS, especially east of the Rockies. Evapotranspiration was unusually high from parts of the Plains to Ohio Valley. Precipitation was near to above normal in this region, so the 1-month SPEI values were comparable to the corresponding SPI. In fact, with the April precipitation wet or only slightly dry across much of the CONUS, the SPEI and SPI values were of similar magnitude in most areas. Even though temperatures were unusually warm across the CONUS for the last 3 to 6 months, precipitation was fairly evenly distributed or wet (except in a few areas) during this period, so the SPEI and SPI maps had similar magnitudes for most areas for much of this period (SPEI maps for the last 1, 3, 6, 12 months) (SPI maps for the last 1, 3, 6, 12 months).

The last 1 to 6 years have been unusually warm across much of the CONUS, especially in the South and West, but also in the Northeast and Midwest (East North Central and Central regions) (state temperature rank maps for the last 1, 2, 3, 4, 5 years). The last 1 to 2 years have been extremely dry in the southern Plains to Upper Mississippi Valley; the last 3 to 4 years have been quite dry in the West to Great Plains; and the last 5 years have been unusually dry across much of the West and southern Plains (state precipitation rank maps for the last 1, 2, 3, 4, 5 years). In the last 1 to 6 years, the SPEI is more extreme than the SPI in the Pacific Northwest but especially in the Southwest to Lower Mississippi Valley. In the western U.S., where drought has dominated for much of the last 20 years, the combination of excessive heat and dryness has resulted in more extreme SPEI values than SPI values in parts of the West for the last 2 to 6 years (SPEI maps for last 12, 24, 36, 48, 60, 72 months) (SPI maps for last 12, 24, 36, 48, 60, 72 months).

The 24-month SPEI for Louisiana is more extreme than the corresponding SPI, ranking driest on record compared to the SPI which is barely in the top 10 driest category.

Regional Discussion

Rio Grande River Basin

During October 2023-March 2024, parts of the Rio Grande River Basin were wetter than normal, parts drier than normal, and parts near normal. But very dry and hot conditions of summer and early fall last year created significant precipitation deficits and expanded drought. April 2024 was mostly drier than normal, with the basin having the 28th driest April in the 1895-2024 record. The last 12 months ranked as the 22nd driest May-April (tied with 2011), but also the second warmest. The last 10 months was the 15th driest July-April, last 11 months (June 2023-April 2024) and 18 months (November 2022-April 2024) 16th driest, and last 48 months (May 2020-April 2024) and 60 months (May 2019-April 2024) seventh driest as well as warmest on record. According to the USDM, 75.8% of the basin was in moderate to exceptional drought at the end of April, which is a little less than the 77.1% at the end of March. Based on the Palmer Drought Index, 91.2% of the basin was in moderate to extreme drought at the end of April, which is more than the end of March but less than the peak of 100% that occurred just last year and many times in the last 30 years, 1950s, and early 1900s.

Upper Mississippi River Basin

The Upper Mississippi River Basin was very dry during spring to fall last year. Above-normal precipitation during December 2023 and January, March, and April 2024 helped lessen precipitation deficits. April 2024 ranked as the tenth wettest April on record, basinwide, and March-April 2024 ranked as the ninth wettest. In spite of the recent wetness, the last 12 months were still the 22nd driest May-April, as well as the warmest May-April on record. In fact, the last 8, 9, 36, 48, and 60 months were all the warmest on record. According to the USDM, 23.8% of the basin was in moderate to extreme drought at the end of April, which is less than the 36.6% at the end of March. Based on the Palmer Drought Index, 19.4% of the basin was in moderate to extreme drought at the end of April, a huge drop compared to the end of March. This is less than the peak last year of 78.0% and much less than the peak of 100% which occurred in the 1970s and several times in the 1930s.

Hawaii

April 2024 was drier than normal across the Big Island and parts of Maui and Molokai, and mostly wetter than normal over Lanai, Oahu, and Kauai. Most of the Hawaiian Islands, except for Kauai and the windward stations on the Big Island, were drier than normal for March-April. The last 3 and 9 to 12 months were dominated by drier-than-normal conditions, with a mixed precipitation anomaly pattern evident at the 4- to 6-month time scale. A mixed anomaly pattern dominated at longer (2-5 years) time scales (precipitation anomaly 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).

Monthly streamflow was near to above normal across most of the main islands. Based on satellite analyses (stressed vegetation, drought stress, VHI), vegetation was stressed on parts of the Big Island, Molokai, and Maui.

Severe drought continued on the Big Island and Maui, with abnormal dryness on Molokai and Lanai. The drought area in Hawaii decreased from 41.6% at the end of March to about 33.4% of the state on the April 30, 2024 USDM map.

Alaska

April 2024 was drier than normal across the eastern three-fourths of Alaska, with some scattered wetter-than-normal stations in the south and west. This pattern extended over the last 2 to 4 months, with dryness limited to the central to south coastal areas at the 6-month time scale. At 9 months, dry conditions extended along the Aleutian chain. Drier-than-normal conditions shifted back to the Cook Inlet to eastern interior areas, and remained far out along the Aleutian chain, at 12- to 24-month time scales, with wetter-than-normal conditions dominating at the long time scales (low elevation station precipitation anomaly maps for the last 1, 2, 3, 4, 6, 9, 12, 24, 36, 48, 60 months) (high elevation SNOTEL station precipitation percentile maps for the last 1, 4, and 7 months) (SNOTEL basin and station percent of normal precipitation maps for the last 1, 4, and 7 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).

April temperatures averaged near to warmer than normal across most of the state, with some cooler-than-normal stations in the southwest. Warmer-than-normal temperatures dominated at the 2- and 3-month time scales. The January-April temperature anomaly pattern was warmer than normal in the west and north, with a mixed anomaly pattern elsewhere. At the 6- to 12-month time scales, it was warmer than normal across the state when compared to the long-term (1925-2024) average. When compared to more recent (1991-2020) normals, cooler-than-normal temperatures were evident in the Cook Inlet to Bristol Bay and Northwest Gulf regions with warmer-than-average temperatures to the east and north because of a pronounced warming trend in recent decades (low elevation station temperature anomaly maps for the last 1, 2, 3, 4, 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).

Monthly streamflow was mostly near to above normal for those streams that aren't frozen, with some below-normal stream levels in the panhandle. Snow still covered most of the state, with snow water content (SWE) near to above normal in most of the state but below normal in the panhandle, northwest, and some interior basins. Satellite observations of vegetative health (stressed vegetation, drought stress, VHI) revealed areas of stressed vegetation, although the analysis was complicated by snow cover. Satellite-based or modeled observations of groundwater and soil moisture (GRACE root zone and GRACE surface soil moisture; SPoRT estimates of soil moisture at four depths [0-10 cm, 10-40 cm, 40-100 cm, 100-200 cm]; Leaky Bucket modeled soil moisture) suggested some dryness was occurring in parts of the south and northeast, but the ground is still mostly frozen; a more accurate determination will be made once the ground thaws.

Alaska was free of drought on the April 30, 2024 USDM map, although some abnormal dryness developed in the southern panhandle.

Puerto Rico and U.S. Virgin Islands

April 2024 was wetter than normal across the U.S. Virgin Islands (USVI) and most of Puerto Rico (PR). Wetter-than-normal conditions dominated the 2- to 4-month time periods. Drier-than-normal areas were evident at 6 to 7 months and more widespread at longer time scales (radar-based precipitation anomaly estimates for the last 1, 2, 3, 4, 6, 7, and 12 months) (low elevation station precipitation anomaly maps for the last 1, 2, 3, 7, 12, 24, 36, 48 months) (climate engine model percent of normal precipitation map for the last month: PR and USVI, Caribbean and Gulf of Mexico region).

Temperatures were generally warmer than normal for April. Root zone analysis indicated that soil conditions were dry across the northwestern and southern coasts of PR, with dryness more evident in the mid-level soil layers compared to shallower and deeper soil layers (root zone soil saturation fraction, SPoRT estimates of soil moisture at four depths [0-10 cm, 10-40 cm, 40-100 cm, 100-200 cm]). Satellite observations of vegetative health (stressed vegetation for PR and USVI, drought stress for PR and USVI, VHI for PR and USVI) revealed few if any areas of stressed vegetation. Monthly streamflow on PR showed near- to above-normal stream levels. In the USVI, groundwater levels declined the first half of April then rose during the second half at St. John and St. Thomas; groundwater levels held steady during the first half of the month then rose at St. Croix. The end-of-April groundwater level continued well in the bottom third of the recent historical record at St. Croix, but was in the upper third at St. John and St. Thomas.

In the USVI, abnormal dryness continued on St. Thomas, while St. Croix and St. John continued free of drought and abnormal dryness. On PR, moderate drought ended with abnormal dryness shrinking to cover about 5.2% of the territory on the April 30, 2024 USDM map.

CONUS State Precipitation Ranks

April 2024 was drier than normal across the Mid-Atlantic coast, parts of the Plains and Southeast, and much of the West, with record dryness locally in Kansas. Seven states had a precipitation rank in the driest third of the historical record for April. None ranked in the top ten driest category, but one came close — North Carolina (13th driest). Above-normal precipitation in eastern Kansas kept that state out of the dry-third category, in spite of the record dryness in other parts of the state.

Parts of the CONUS have had very dry conditions at various times during the past 4 months, but the location of the dryness varied from month to month and some of the dry areas had wetter-than-normal conditions during intermittent months (low elevation station precipitation anomaly maps for the last 2, 3, and 4 months) (climate division precipitation rank maps for the last 3 and 4 months). Persistently dry areas include parts of the central and southern Plains, northern Plains to Pacific Northwest, and the Ohio to Mid-Mississippi Valleys. Those states that were dry experienced enough precipitation over other parts of the state to balance out the dryness. So, only 4 states ranked in the driest third of the 1895-2024 record for February-April and none were in the driest third of the historical record for January-April; no state ranked in the top 10 driest category for these two time scales.

The last 6 to 12 months were a little drier but had a similar precipitation anomaly pattern as the past 4 months, i.e., the location of the dryness varied from month to month and some of the dry areas had wetter-than-normal conditions during intermittent months (low elevation station precipitation anomaly maps for the last 6, 7, 9, 10, and 12 months) (climate division precipitation rank maps for the last 6 and 12 months). Persistently dry areas include parts of the Plains, Southwest, Pacific Northwest, and Ohio, Tennessee, and Mississippi Valleys. Those states that were dry experienced enough precipitation over other parts of the state to balance out the dryness. So, only 4 states ranked in the driest third of the 1895-2024 record for November-April and 13 were in the driest third of the historical record for May-April; no state ranked in the top 10 driest category for these two time scales.

Agricultural Belts

During April 2024, the Primary Hard Red Winter Wheat agricultural belt was warmer than normal and mostly drier than normal. The month ranked as the 54th driest and 18th warmest April, regionwide, in the 1895-2024 record.

October marks the beginning of the growing season for the Primary Hard Red Winter Wheat belt. October 2023-April 2024 was warmer than normal with a mixed precipitation anomaly pattern. The period ranked as the 51st wettest and fifth warmest October-April, regionwide, on record.

During April 2024, the Primary Corn and Soybean agricultural belt was warmer than normal and mostly wetter than normal. The month ranked as the tenth wettest and 20th warmest April, regionwide, in the 1895-2024 record.

March marks the beginning of the growing season for the Primary Corn and Soybean belt. March-April 2024 was mostly warmer and wetter than normal. The period ranked as the tenth warmest and 21st wettest March-April, regionwide, in the historical record.

According to the U.S. Department of Agriculture (USDA), as of April 30, 2024, drought affected approximately 17% of barley production, 19% of corn production, 8% of cotton production, 50% of sorghum production, 17% of soybean production, 27% of spring wheat production, 28% of winter wheat production, 12% of hay acreage, 17% of the cattle inventory, 9% of the milk cow inventory, and 14% of the sheep inventory.

Based on April 28 USDA statistics, 16% of the nation's winter wheat crop was in poor to very poor condition, and 25% of the nation's topsoil and 29% of the subsoil were short or very short of moisture (dry or very dry).

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 [ROP], American Samoa, basinwide), April 2024 was drier than normal in parts of the Marianas, FSM, and Marshalls, but near to wetter than normal in the Republic of Palau, American Samoa, and other parts of the FSM, Marshalls, and Marianas.

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 Marianas, Marshalls, and western FSM. April precipitation was above the monthly minimums in American Samoa, Palau, most of the FSM, and southern parts of the Marshalls and Marianas. 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 2024, which was in the wet season for American Samoa, Kapingamarangi, Chuuk, Pohnpei, and Kosrae, and in the dry season for western, northern, and eastern parts of the Micronesia region. Precipitation was below the monthly minimum but above normal (1981-2010 normal), because the normals are low, at:

  • Ailinglaplap: April 2024 precipitation 7.73 inches, April normal mean 7.32 inches.

Precipitation was above the monthly minimum but below normal (1981-2010 normal), because the normals are high, at:

  • Kosrae: April precipitation 14.64 inches, April normal mean 19.52 inches, April normal median 17.51 inches.
  • Nukuoro: April precipitation 13.15 inches, April normal mean 15.43 inches.
  • Woleai: April precipitation 8.24 inches, April normal mean 8.43 inches.
  • Jaluit: April precipitation 8.18 inches, April normal mean 11.84 inches.
  • Pago Pago: April precipitation 10.83 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).

Pacific Island Percent of 1981-2010 Normal Median Precipitation
Station Name May
2023
Jun
2023
Jul
2023
Aug
2023
Sep
2023
Oct
2023
Nov
2023
Dec
2023
Jan
2024
Feb
2024
Mar
2024
Apr
2024
May-
Apr
Chuuk191%118%130%118%112%110%141%100%100%76%40%99%109%
Guam NAS916%146%86%132%98%152%84%107%59%62%78%283%124%
Kapingamarangi137%145%162%121%256%117%153%74%188%206%196%99%136%
Koror165%77%145%125%130%108%85%67%136%140%48%184%108%
Kosrae87%166%132%104%123%153%163%44%90%119%96%84%93%
Kwajalein345%143%45%81%61%103%156%111%53%52%196%80%111%
Lukonor61%116%75%74%115%136%81%94%64%76%153%164%88%
Majuro102%105%70%95%56%86%101%70%57%74%16%111%80%
Pago Pago168%109%102%42%156%91%36%195%142%201%71%115%110%
Pohnpei145%121%148%219%156%83%178%48%50%170%91%116%123%
Saipan225%92%46%142%109%92%133%158%74%79%83%67%104%
Yap131%121%168%145%70%88%79%41%90%55%14%33%94%
Pacific Island Precipitation (Inches)
Station Name May
2023
Jun
2023
Jul
2023
Aug
2023
Sep
2023
Oct
2023
Nov
2023
Dec
2023
Jan
2024
Feb
2024
Mar
2024
Apr
2024
May-
Apr
Chuuk21.57"13.73"15.56"15.23"13.07"12.70"14.93"11.22"10.05"5.49"3.30"12.38"149.23"
Guam NAS31.15"9.00"8.69"19.47"12.46"17.40"6.18"5.49"2.38"1.88"1.62"7.17"122.89"
Kapingamarangi16.59"20.04"22.86"9.87"25.45"9.55"14.14"7.33"17.18"19.05"22.43"13.53"198.02"
Koror19.53"13.44"26.81"16.86"15.26"12.80"9.65"7.46"13.85"11.97"3.56"13.44"164.63"
Kosrae15.41"24.30"19.67"14.72"17.52"16.79"22.60"7.06"15.04"15.43"15.34"14.64"198.52"
Kwajalein23.18"9.93"4.45"7.86"6.60"11.46"17.65"7.42"1.66"1.37"4.61"4.19"100.38"
Lukonor7.13"13.55"11.89"10.33"11.63"15.43"7.40"10.54"5.42"6.83"14.20"18.58"132.93"
Majuro10.35"11.56"7.87"11.07"6.27"10.98"13.51"7.96"4.38"5.11"1.08"10.43"100.57"
Pago Pago16.19"5.81"5.64"2.26"10.18"8.45"3.69"25.00"18.99"24.09"7.61"10.83"138.74"
Pohnpei29.02"17.94"22.76"31.21"19.57"12.71"26.39"7.76"6.65"16.27"12.02"21.36"223.66"
Saipan5.35"3.34"4.13"18.62"11.03"9.80"7.44"6.07"1.87"2.05"1.57"1.76"73.03"
Yap10.28"14.59"25.35"21.43"9.46"10.74"6.95"3.53"5.73"2.84"0.64"1.83"113.37"
Pacific Island 1981-2010 Normal Median Precipitation (Inches)
Station Name May
2023
Jun
2023
Jul
2023
Aug
2023
Sep
2023
Oct
2023
Nov
2023
Dec
2023
Jan
2024
Feb
2024
Mar
2024
Apr
2024
May-
Apr
Chuuk11.30"11.66"11.98"12.86"11.71"11.51"10.61"11.25"10.10"7.25"8.32"12.47"136.77"
Guam NAS3.40"6.18"10.14"14.74"12.66"11.44"7.38"5.11"4.01"3.03"2.07"2.53"99.09"
Kapingamarangi12.08"13.78"14.15"8.13"9.93"8.19"9.27"9.84"9.15"9.27"11.43"13.64"145.85"
Koror11.83"17.48"18.53"13.50"11.77"11.84"11.39"11.16"10.18"8.56"7.44"7.32"152.90"
Kosrae17.75"14.64"14.91"14.22"14.22"10.94"13.83"16.11"16.67"12.93"16.06"17.51"213.87"
Kwajalein6.72"6.93"9.87"9.74"10.74"11.18"11.28"6.66"3.16"2.64"2.35"5.26"90.41"
Lukonor11.69"11.65"15.93"14.04"10.15"11.32"9.08"11.27"8.41"8.93"9.26"11.31"151.36"
Majuro10.11"11.01"11.17"11.69"11.17"12.73"13.44"11.39"7.74"6.88"6.58"9.42"125.25"
Pago Pago9.66"5.33"5.55"5.38"6.53"9.26"10.14"12.84"13.34"12.00"10.68"9.39"125.57"
Pohnpei19.96"14.81"15.43"14.26"12.55"15.27"14.83"16.08"13.18"9.55"13.17"18.41"182.36"
Saipan2.38"3.62"8.91"13.13"10.09"10.62"5.61"3.85"2.53"2.59"1.89"2.63"70.25"
Yap7.85"12.04"15.08"14.82"13.50"12.18"8.83"8.51"6.39"5.19"4.56"5.63"120.31"

As measured by percent of normal precipitation, Kosrae and Yap were drier than normal at all time scales in the short term (April, the last 3 months [February-April], and the year-to-date [January-April]) and long term (last 12 months [May 2023-April 2024]). Kwajalein and Saipan were drier than normal in the short term and wetter than normal in the long term. Lukunor was wetter than normal in the short term and drier than normal in the long term. Majuro was wetter than normal for April but drier than normal for the other 3 time scales. Chuuk was drier than normal for the last 3 to 4 months but near to wetter than normal for April and in the long term. Guam was drier than normal for the year to date but wetter than normal for the other 3 time scales. Airai, Kapingamarangi, Pago Pago, 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, April and the last 2 to 12 months were drier than normal across the main islands except Guam. Wetter-than-normal conditions dominated at longer time scales (percent of normal precipitation maps for the last 1, 2, 3, 7, 12, 24, 36, 48 months).

Based on percent of normal average (instead of normal median values), the Marshall Islands were mostly drier than normal for April and the last 2 to 12 months, with a mixed anomaly pattern dominating at longer time scales (percent of normal precipitation maps for the last 1, 2, 3, 7, 12, 24, 36, 48 months).

According to the April 30 USDM produced for the USAPI:

  • In the Marianas, severe drought worsened to extreme drought on Saipan, severe drought worsened to extreme drought then recovered back to severe drought on Guam, and moderate drought continued on Rota;
  • In the FSM, extreme drought worsened to exceptional drought on Yap, severe drought worsened to exceptional drought on Ulithi, moderate drought worsened to extreme drought then recovered to severe drought at Woleai, moderate drought improved to abnormal dryness at Chuuk, and abnormal dryness ended at Pingelap;
  • In the Marshalls, extreme drought worsened to exceptional drought at Wotje, severe drought worsened to extreme drought then improved to moderate drought at Majuro, moderate drought continued at Kwajalein, abnormal dryness continued at Ailinglaplap, and abnormal dryness ended at Jaluit; and
  • Abnormal dryness ended at Palau.

The level of the reservoir on Majuro began the month at 20.3 million gallons, steadily declined to a minimum level of 17.8 million gallons on the 13th, then steadily rose to end the month at 24.4 million gallons. If the reservoir dips below 28.8 million gallons, drought becomes a concern. Satellite observations of vegetative health (drought stress, stressed vegetation, VHI) revealed areas of stressed vegetation on Guam.

The National Weather Service (NWS) office in Guam issued two Drought Information Statements (DGT) for drought for April (on April 12 and 26). Drought impacts included:

  • water catchment levels are low or nearly empty on some islands. Water shortages for communities are occurring, especially for islands in Yap State and the northern RMI. Water shortages occurred in western Chuuk State;
  • agricultural strain is occurring on islands across Yap State, where taro patches are drying up, coconuts are drying out, and there have been many reports of yellowing crops;
  • wildfires have been reported on Guam, Saipan, Palau, Pohnpei, and Yap;
  • the Republic of Palau remains on Stage 1 of the Drought Action Plan.

April 2024 precipitation ranks ranged from very dry to wet with some mid-range, based on data available at the time of this report. Some locations have had dry conditions for several months:

  • Ulithi: second driest April (in a 42-year record) and March-April, fifth driest November-April, and seventh driest September-April.
  • Yap: second driest March-April (in a 73-year record), seventh driest April, and fifth driest November-April and September-April.
  • Kosrae: tenth driest April (54 years), and fifth driest December-April.
  • Nukuoro: 16th driest April (41 years), but fifth driest February-April.
  • Pingelap: 24th driest April (40 years), but fifth driest December-April back through August-April and June-April (all six time scales), fourth driest July-April, and sixth driest May-April (12-month period).
  • Woleai: 20th driest April (45 years), but sixth driest December-April and seventh driest February-April and January-April.
  • Jaluit: 16th driest April (41 years), but sixth driest August-April and July-April, and fifth driest June-April and May-April.
  • Wotje: 24th driest April (41 years), but sixth driest November-April and July-April.
  • Kwajalein: 20th wettest April (72 years), but fifth driest July-April (10-month period).
  • Majuro: 36th driest April (70 years), but sixth driest May-April (12-month period), fourth driest June-April, and third driest July-April.

At the wet end of the scale:

  • Kapingamarangi had the 17th driest April (32 years), but wettest July-April, June-April, and May-April.
  • Pohnpei had the 50th driest (24th wettest) April (73 years) but fifth wettest May-April.
  • Guam had the 59th driest (tenth wettest) April (68 years) and third wettest May-April (12-month period), but 18th driest November-April (6-month period).

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 2024, November 2023-April 2024 (last 6 months), and May 2023-April 2024 (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.

April 2024 USAPI Precipitation Ranks (1 = driest)
StationApril 2024Nov 2023-Apr 2024May 2023-Apr 2024Period of Record
RankYearsRankYearsRankYears
Ailinglaplap1841223924381981-2024
Airai5973327355711951-2024
Chuuk4273197342721951-2024
Fananu--7--6--22003-2023
Guam5968186765671957-2024
Jaluit164112395381981-2024
Kapingamarangi1732252719191962-2024
Kosrae105494415371954-2024
Kwajalein2072347243721952-2024
Lukunor3740213913271981-2024
Majuro36709706691954-2024
Mili--39--36--341981-2024
Nukuoro1641113916381981-2024
Pago Pago3459455840581966-2024
Pingelap24405366341981-2024
Pohnpei5073417368721951-2024
Saipan1844193519351981-2024
Ulithi24253823371981-2024
Utirik--19--8--41985-2020
Woleai2045935--261968-2024
Wotje244163812371981-2024
Yap77357322721951-2024
Map of USAPIApril 2024 Precipitation (Inches)
Map of USAPI April 2024 Percent of Normal Precipitation
Map of USAPI February 2024-April 2024 Percent of Normal Precipitation
Map of USAPI January-April 2024 Percent of Normal Precipitation
Map of USAPI May 2023-April 2024 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, following a very wet winter and early spring, precipitation in April was mostly below average across the Southeast. The driest locations were found across northern portions of Alabama, Georgia, and South Carolina, central and eastern portions of North Carolina, southern and eastern portions of Virginia, and the southern half of Florida, where monthly totals were 2 to 4 inches (51 to 102 mm) below average (25 to 75 percent of normal). In contrast, above-average precipitation was recorded across central and southern portions of Georgia and the central Panhandle of Florida. Temperatures were mostly above average across the Southeast in April, except across parts of Alabama, southern Georgia, and most of Florida, where temperatures were near to slightly below average for the month. Temperatures were also above average across Puerto Rico and the U.S. Virgin Islands, with daily heat index values exceeding 100 degrees F (37.8 degrees C) in San Juan, prompting heat advisories from the National Weather Service. Precipitation was above average across Puerto Rico and the U.S. Virgin Islands.

Following several months of above-average precipitation, April began with nearly the entire region free of any drought or abnormal dryness. However, mostly warm and dry weather during the month resulted in an expansion of abnormal dryness (D0) across eastern and central North Carolina and southern portions of the Florida Peninsula. Abnormal dryness (D0) also emerged across southern Virginia, northern portions of Alabama, Georgia and South Carolina, extreme southwestern Virginia, and around Augusta, GA. Moderate (D1) drought also emerged across southeastern Florida from around Lake Okeechobee to Cape Canaveral. By the end of April, nearly 25 percent of the region was in at least some abnormal dryness or drought. Dry weather forced some farmers to begin using irrigation and delayed the planting of cotton and peanuts across parts of the Carolinas. There is concern that dry land corn could be negatively impacted if the dry weather pattern continues. Dry conditions also slowed pasture growth in parts of Florida. In contrast, moderate (D1) drought was eliminated across Puerto Rico, with only a small pocket of abnormal dryness (D0) remaining in the extreme northwest corner of the island. For the second straight month, abnormal dryness (D0) persisted on Saint Thomas, while Saint John and Saint Croix remained free of any drought or abnormal dryness.

South

As explained by the Southern Regional Climate Center, severe weather was prevalent in April with several instances of tornadoes, heavy rain, and flooding across the Southern region. Temperatures were above normal for the entire Southern region during April, with most stations averaging two to four degrees F above normal, while April precipitation amounts were mixed across the region. Stations in northeastern Texas, much of Louisiana, central Mississippi, southern Arkansas, southeastern Oklahoma, and isolated portions of the Texas Panhandle received between 150 and 300 percent of normal precipitation, while stations in Deep South Texas, Far West Texas, western Oklahoma, much of Arkansas, and Tennessee were below normal during April.

During April, drought conditions remained steady across much of the region. Improvements were noted in western Tennessee, northwestern Mississippi, East Central Arkansas, West Central Louisiana, and isolated portions of Central Texas. Degradations in drought conditions were prevalent across northern Oklahoma, northern Arkansas, and South Central Texas. As of April 30th, according to the USDM, Louisiana, Mississippi, and Tennessee are drought-free and there is no Exceptional Drought anywhere in the Southern region. With recent precipitation across the region, soil moisture has continued to rebound with the USDA reporting mostly adequate subsoil moisture, as of April 28th, in Louisiana (83 percent), Tennessee (81 percent), and Mississippi (70 percent). The only state with less than 50 percent of land having adequate subsoil moisture is Texas (44 percent). Worsening drought conditions in Santa Rosa, Texas have led to the shutdown of the only operating sugar mill in the state due to lack of adequate water supply.

Midwest

As described by the Midwest Regional Climate Center, an active weather pattern brought widespread severe wind, hail, and tornadoes to the Midwest on at least eight days in April, plus a few additional days with isolated severe weather. The preliminary average April temperature for the Midwest was 50.9 degrees F (10.5 degrees C), which was 2.2 degrees F (1.2 degrees C) above the 1991-2020 normal, and preliminary April precipitation totaled 4.89 inches (124 mm) for the Midwest, which was 1.22 inches (31 mm) above normal, or 133 percent of normal. Temperatures were 2-6 degrees F (1.1-3.3 degrees C) above normal across the region, with the warmest anomalies across the eastern and southern Midwest. A wide swath of 5-10 inches (125-254 mm) of precipitation fell across most of Missouri, Illinois, Indiana, and Ohio. The rest of the region had about 2-5 inches (50.8-125 mm) of precipitation in April.

Regional drought improvement that began in March continued through April. The month started with about 62 percent of the region in drought or abnormally dry and ended with about 34 percent affected. Iowa remained the most affected state, although drought severity lessened throughout the month. In the upper Midwest, drought conditions affected northern Minnesota, Michigan's Upper Peninsula, and portions of Wisconsin. Across the lower Midwest, drought conditions were present in portions of Missouri, far southern Illinois, and extreme western Kentucky. Indiana and Ohio were completely free of drought or abnormal dryness by month's end.

Northeast

As summarized by the Northeast Regional Climate Center, while conditions were variable, April leaned to the warm and wet side of normal for the Northeast as a whole. The Northeast's average temperature for April was 47.4 degrees F, 1.2 degrees F warmer than normal, and regional precipitation was 4.16 inches for the month, which was 111 percent of normal. Seven of the 12 Northeast states experienced a drier-than-normal April, with precipitation ranging from 67 percent of normal in Delaware to 156 percent of normal in Pennsylvania.

The USDM from April 2 showed less than one percent of the Northeast in moderate drought and three percent as abnormally dry. Beneficial precipitation, particularly during the first half of the month, eased moderate drought in western New York and on Nantucket, Massachusetts, allowing the Northeast to be free of drought for the first time since spring 2023. Additionally, abnormal dryness was erased from Nantucket and contracted in western New York. The USDM from April 30 showed two percent of the Northeast as abnormally dry.

High Plains

As discussed by the High Plains Regional Climate Center, severe weather significantly ramped up in April, with one of the more impactful outbreaks in recent years striking the southern parts of the region at the end of the month. Heavy precipitation and downpours with the multiple rounds of storms led to tremendous recorded totals. The northern High Plains and eastern Kansas received normal to above normal precipitation this month, while others were not as fortunate. Parts of western Kansas are on their second month in a row of well below to near zero amounts. Dodge City tied with 1909 for their driest April, while also ranking 3rd for driest March-April. Nearby places such as Bucklin, Cimarron, and Offerle ranked driest for the two months, with those locations only receiving around 0.25 inch (0.64 cm) of precipitation. Warmer temperatures returned this month, with the region experiencing slightly above-normal temperatures.

The heavy precipitation this month improved drought conditions for some, while others were not as fortunate. Up to 2 classes of change occurred on both ends of the spectrum, with an overall reduction of 6 percent of D0 to D4 (abnormally dry to exceptional drought conditions) in the High Plains. After steadily climbing out of a significant drought, Kansas took a big step backward this month. At the beginning of April, less than 2 percent of the state was experiencing D2 (severe drought). Over the month, it rapidly rose to over 27 percent. Much of the western part of the state slipped back into drought conditions, after a short period of being close to drought-free. The Dakotas received beneficial precipitation this month, reducing the extent of D0 conditions across both states. Most of South Dakota is drought-free, while drought conditions in northeastern North Dakota remain firmly entrenched. Elsewhere in the region, other improvements and degradation were observed.

West

As summarized by the Western Regional Climate Center, the month of April was marked by average temperatures across most of the western United States and no areas experiencing below-average temperatures. Some areas of warmer-than-average temperatures occurred in the northern and northwestern states in the region. Precipitation records were broken in multiple states for both lack of precipitation and record rainfall totals. Record-low snowpack continues to be a problem for areas in the northern Rockies.

The month had near record and above record dryness in western Montana, most of New Mexico, and scattered across Washington. Montana had many locations reporting averages more than an inch below normal. Glendive recorded its third driest April with a 0.03 inch total (1.47 inches below normal), Plevna was 1.44 inches below normal, Circle was 1.15 inches below normal, and Terry was 1.38 inches below normal. New Mexico had four stations that tied their driest April records — Carlsbad (0.45 inch below normal), Gran Quivira (0.56 inch below normal), Yeso (0.78 inch below normal), and Hillsboro (0.35 inch below normal). Washington also had a few below-average precipitation totals in Seattle (2.29 inches below normal), Mazama (0.74 inch below average), and Walla Walla (1.58 inches below normal). On the other hand, areas in Arizona, Idaho, and Nevada had above average precipitation totals for the month of April.

Below-average snowpack in Montana threatens water supply: This winter Montana has had its worst snowpack in 25 years. Upcoming weather conditions are not favorable in helping the water supply with summer streamflow predictions estimated at well below normal for most of the state. The snowpack total was nearly 5 inches of snow water equivalent below normal by the second week of April. Montana's current snowpack is only at 12 inches of snow water equivalent, 74 percent of normal. The Bear Paw snowpack is already entirely gone with many other locations sitting between 45 to 69 percent of average.

According to the USDM at the end of April, 20.6 percent of the West was in drought, a slight improvement from last month. Areas of extreme (D3) and exceptional (D4) drought are still found in southern New Mexico and western Montana. Areas of dryness and drought are found in all western states, however most of them are only in moderate (D1) or abnormally dry (D0) conditions.

Alaska summary: Temperatures were above normal for the western Interior and Southeast with temperatures in those locations ranging from two to seven degrees Fahrenheit above normal. Eastern and northeastern Alaska, and Kodiak Island Alaska, recorded above-average precipitation totals. Tied record dryness was seen in central and western Alaska, where three stations reported 0 inches for the month of April, including Tanana (0.3 inch below average), Northway (0.22 inch below average), and Chicken (0.3 inch below average). From the USDM, abnormally dry conditions (D0) can be found in the southeast region with a risk of degradation.

Hawaii summary: Hawaii saw average temperatures across most of the state for the month of April with sites only being a degree or two Fahrenheit warmer. Kauai Island saw above-average precipitation totals with Lihue setting a record 13.14 inches (11.11 inches above average), about a 650 percent increase of normal. The rest of the islands saw average precipitation totals. Drought conditions improved for the state with only 33.4 percent being in D1 or higher, an 8.6 percent decrease from March. Areas of severe drought (D2) are occurring on the Big Island and Maui.

Additional Resources


Citing This Report

NOAA National Centers for Environmental Information, Monthly Drought Report for April 2024, published online May 2024, retrieved on May 22, 2024 from https://www.ncei.noaa.gov/access/monitoring/monthly-report/drought/202404.