The wet May pattern continued to alleviate or bring an end to drought across the Northeast. Severe to extreme drought persists for central to south Florida although locally heavy showers fell across the east-central Florida Peninsula as the rainy season begins to ramp up. Widespread precipitation (2 inches or more) supported improvements to the Central and Southern Great Plains. During recent weeks, drought developed across portions of southwestern Iowa, northern Illinois, and northwestern Indiana. Short-term drought expanded across the Pacific Northwest and intensified for southern Utah and northwestern Colorado during mid to late May. From May 20-26, above-normal temperatures were limited to the southern tier of the contiguous U.S. 7-day temperatures averaged 4 to 10 degrees F below normal across the Northeast, Corn Belt, and Northern to Central Great Plains. Alaska and Puerto Rico are drought-free, while drought of varying intensity continues for parts of Hawaii.
Drought improvement continued into late May as widespread precipitation was observed from New England south to the Mid-Atlantic. The heaviest precipitation (2 to 6 inches) soaked much of eastern Massachusetts and Rhode Island, supporting the elimination of nearly all of the abnormal dryness (D0) and moderate drought (D1). However, precipitation amounts were lower across Cape Code and 28-day average streamflows remain below the 20th percentile, supporting long-term drought. Frequent precipitation this month increased soil moisture and 28-day average streamflows across southeastern Pennsylvania, Maryland, and northern West Virginia where pockets of 1-category improvements were made. However, the NDMC long-term drought blend and low groundwater support the continuation of abnormal dryness (D0) and moderate drought. Severe long-term drought (D2) was maintained in Baltimore County, Maryland due to the lack of a favorable response in groundwater.
A continued wet pattern and soil moisture recovery led to a reduction in abnormal dryness (D0) and moderate drought (D1) for parts of eastern Georgia, the Carolinas, and Virginia. Despite the beneficial precipitation this month, a long-term drought signal characterized by low groundwater support maintaining moderate drought (D1) for parts of northern Virginia. Florida’s rainy season appears to be underway as thunderstorms with locally heavy rainfall brought drought relief to east-central portions of the state. However, west-central Florida remained mostly dry which led to a 1-category degradation. Extreme drought (D3) continues to affect southwestern Florida and the Everglades where water levels are very low.
Heavy rainfall (2 inches or more) prompted a 1-category improvement to ongoing drought areas of south-central and southeastern Texas. Despite this recent heavy rainfall, levels in the long-term monitoring wells of Bexar and Medina Counties remain at all-time lows. In addition, many of the 28-day average USGS streamflows are below the 5th percentile, supporting the D3-D4 depiction. Since the SPIs dating back 6 months are neutral and considering the major impact is hydrological, the drought impact was changed to long-term only. With drought improvement for northwestern Oklahoma this past week, nearly all of Oklahoma and northern to eastern Texas are drought-free. The Lower Mississippi Valley and Tennessee Valley are also drought-free with surplus 30 to 90-day precipitation.
On May 20 and 21, a low pressure system resulted in a widespread swath of 1 to 2 inches of precipitation from Minnesota southeastward to Wisconsin, leading to 1-category improvements. However, western to southern Iowa, northern Illinois, northern Indiana, and adjacent southwestern Michigan received lower precipitation amounts this past week. Increasing 30-day precipitation deficits and declining soil moisture led to an expansion of moderate drought (D1) and abnormal dryness (D0) for these areas. Northern Missouri has also been on the drier side during the past 30 days which prompted an increase in D0 coverage.
From May 24-26, widespread precipitation (1 to 3 inches, locally more) resulted in a 1-category improvement to portions of southwestern South Dakota, Nebraska, Kansas, and northeastern Colorado. Much cooler temperatures accompanied this widespread precipitation which contributed to topsoil moisture recharge. Based on multiple indicators such as the SPI at various time scales and soil moisture, severe (D2) to extreme (D3) drought was reduced in coverage across central to western Nebraska along with adjacent areas of southwestern South Dakota. Although precipitation was lighter across southeastern Colorado, SPIs at multiple time scales, soil moisture, and VegDri no longer support any D1. Southern Nebraska and northern Kansas missed out on this past week’s precipitation and a couple of small 1-category degradations were made. A 1-category degradation was also warranted for western Colorado based on 90 to 180-day SPI.
Based on 6-month SPI, water-year-to-date (October 1, 2024 to May 26, 2025) precipitation deficits, and 28-day average streamflow, moderate drought (D1) was expanded to include more of southwestern Washington. Increasing 30 to 90-day precipitation deficits, low 28-day average streamflows, and declining soil moisture led to the introduction of D1 to parts of northwestern and northeastern Oregon. The 6-month SPI supported the expansion of severe drought (D2) coverage across southwestern Utah. Although precipitation was light this past week, SPIs dating back 120 days along with more favorable soil moisture indicators led to improvements across southwestern and eastern Montana. Conversely, in northwest Montana, D1 was degraded to D2 based on 120-day SPI and declining soil moisture. To the east of the Sierra Nevada Mountains, abnormal dryness (D0) was expanded to the south of Lake Tahoe due to drier-than-normal conditions since April.
From May 20-26, the heaviest precipitation (more than 2 inches) was observed across northwestern Puerto Rico. During the past 30 days, precipitation averaged at or above-normal with many 28-day average streamflows above the 90th percentile. Therefore, Puerto Rico remains drought-free.
The U.S. Virgin Islands continue to remain free of drought. St. Croix Island received the most precipitation of the three islands, ranging from 0.14” to 1.43” of rain. Water levels rose by 0.2 ft for Adventure 28 Well as a result. Both St. John and St. Thomas received under 0.25” of rain for all CoCoRaHS stations located throughout each island. Because of this, water levels for the Susannaberg DPW 3 and Grade School 3 wells have lowered by approximately 0.6 ft.
Frequent precipitation resulted in the removal of lingering abnormal dryness (D0) in southeastern Alaska with only a small D0 area remaining to the north of Anchorage.
No changes were made to Hawaii this week with extreme drought (D3) designated for parts of the Big Island. Moderate (D1) to severe (D2) drought are posted for Maui, Molokai, and Oahu. Kauai is mostly drought-free.
Drought severity remains the same for the Republic of the Marshall Islands. However, it appeared that precipitation wasn’t scarce for most islands. Ailingalapalap, Jaluit, and Majuro have received 1.5”, 1.65”, and 2.09” of rain, respectively. Mili and Wotje, on the other hand, have received little rain this week, at 0.24” and 0.31”, respectively. Because of this, they will remain in extreme drought. Majuro could become free of drought and dryness if adequate precipitation continues next week.
Rainfall totals for the Federated States of Micronesia were inadequate for most islands. Islands such as Chuuk Lagoon, Lukunor, and Pingelap have received only 0.33”, 0.1”, and 0.09” of rain, respectively. However, Chuuk and Lukunor have received adequate precipitation in the last few weeks and will remain drought and dryness free. Pingelap remains in severe drought. Higher but also inadequate rainfall totals were recorded for Kapingamarangi, Nukuoro, and Pohnpei, at 1.51”, 1.5”, and 1.65” of rain respectively. Kosrae and Yap received plentiful rain, at 2.73” and 2.43”, respectively. This rain was particularly beneficial for Yap, which is in moderate drought. The Republic of Palau has also received beneficial rain. Koror has received 2.31” of rain while the WSO in Palau received 2.9” of rain.
The Mariana Islands continue to face severe drought. Guam received a 1-category degradation to D3 (extreme drought). Most grassland areas on the island are 80-90% dry. NDVI values ranged between 0.45 and 0.65. Wildfires continue to plague the island even with low winds. However, Guam has received a second instance of rain this month at 0.24”. Rota has received only 0.39” of rain this week. Rota also remains in extreme drought. Saipan has received 0.61” of rain at the Saipan International Airport, while the AMME NPS Saipan has received only 0.22” of rain. Saipan will remain in D2 due to a lack of adequate precipitation.
Meanwhile, there is no shortage of precipitation for the American Samoa. The Pago Pago International Airport received 5.99” of rain this week. A whopping 12.49” of rain fell in the Siufaga Ridge, while the Toa Ridge received 9.02” of rain this week. American Samoa will remain drought and dryness free.
Looking Ahead
A low pressure system and trailing front are forecast to maintain the wet pattern along the East Coast with the Weather Prediction Center depicting 1 to 2 inches of precipitation from the Mid-Atlantic north to England through June 2. Much-needed precipitation (locally more than 1 inch) is expected for the Florida Peninsula. From May 29 to June 2, mostly dry weather is forecast across the Midwest. By June 2, a low pressure system is forecast to develop and bring another round of precipitation to the Northern and Central High Plains. Much above-normal temperatures and potential record heat are predicted to affect California and the Great Basin to end May.
The Climate Prediction Center’s 6-10 day outlook (valid June 3-7, 2025) favors above-normal precipitation for the Florida Peninsula, Middle to Upper Mississippi Valley, and Great Plains. The precipitation outlook leans towards above-normal precipitation for much of the West. Elevated below-normal precipitation probabilities are forecast across the Mid-Atlantic and Northeast. Alaska and Hawaii are favored to be on the wetter side during the first week of June. Above-normal temperatures are favored from the Mississippi Valley to the East Coast, while below-normal temperatures are more likely throughout the West and Alaska. A slight lean towards above-normal temperatures are forecast for most of Hawaii.