Weather and Climate
Summary and Forecast
May 2026 Report
Gregory V. Jones, Ph.D.
May 3, 2026
Summary:
- April was warmer than average* over most of the West. However, frost occurred near mid-month for many valley locations growing winegrapes in the west and throughout eastern US wine regions.
- After a dry March, April saw a return of spring rain and even some snow in California and portions of the inland PNW. Drier than normal conditions remained in the southwest, most of the Plains, and in portions of the Rockies, Cascades, and western Washington.
- Drought conditions continue for many areas of the country, with the western US and the southeast seeing the most extreme and prolonged drought. The seasonal outlook calls for further development of drought in the west, while the southeast is likely to see drought conditions improve.
- A ridge is building across the Gulf of Alaska and the PNW while pushing a low pressure area south off of California. As the low slowly moves east, some rain for California over the next few days is likely while the PNW warms to above average temperatures.
- The May forecast for the West is pointing to mostly warm and dry, especially across the PNW.
- Heading into the first half of summer, the 90-day forecast is pointing to a high likelihood of a warmer and drier western US. Very warm ocean temperatures and a developing El Niño in the Tropics are likely to lead to both a warmer summer and an increase in the monsoon flow, which could increase the likelihood of thunderstorms over much of the western US during wildfire season.
*Note that all references to normal or averages in this report are to the 1991-2020 climate normal for each weather/climate parameter unless stated otherwise. See this website for more information on climate normals.
For a PDF of this report, click here.
Past Month and Year to Date:
April brought largely warmer than average temperatures to the western US (Figure 1). Most regions experienced temperatures during April that were from 0.5-3.0 degrees above average, although scattered areas along the southern California coast, portions of Arizona, and the central Rockies saw temperatures closer as much as 3-4 degrees above average (Figure 1). Much of the rest of the country was also warmer than average, especially from Texas into the Ohio River Valley and southeast where temperatures ranged from 4-7 degrees above average in April (not shown). However, averages don’t tell the whole story as large areas of the eastern US and PNW saw untimely frosts in April.
Precipitation amounts in the western US varied across the region with much of central California, the inland PNW, and portions of the Rockies seeing 130-300% of average rainfall, while areas of the southwest, western Oregon and Washington, and the Plains saw 0-70% of normal precipitation (Figure 1). The rest of the country also saw strong regional variations in precipitation during April with the Plains and southeast seeing below 50% of normal precipitation, while the dominant storm track for the month brought significant precipitation (150-300% of normal) from severe weather outbreaks that spawned numerous tornadoes from Texas, northeast into the Mississippi River valley and into the Great Lakes (not shown).
Figure 1 – Western US April 2026 temperature departure from normal (left) and percent of normal precipitation (right; images from WestWide Drought Tracker, Western Region Climate Center; University of Idaho).
January through April temperatures are running largely between 1 to nearly 10 degrees above average across the western US (Figure 2). The southwest and most of the Rockies have seen the warmest conditions so far this year, while western Oregon and Washington have seen temperatures 1-2 degrees above average. The rest of the country continues to experience largely warmer than average temperatures since the first of the year, running 1-3 degrees above average from Texas and the Mississippi River valley eastward. The northern to central Plains, western Great Lakes, central Atlantic states, and Florida have seen closer to average or slightly cooler year to date conditions (not shown).
Year to date precipitation over the west has been mixed, with most regions seeing a drier than normal start to the year (Figure 2), although isolated areas in the inland PNW, northern Rockies, and southern Arizona and New Mexico have been wetter than normal. Year to date drier than average conditions are also found in the central to northern Plains, the southeast, and Florida (not shown). The dominant storm track over the first four months of the year has been from Texas into the Ohio River valley, which has brought roughly 150-300% of average precipitation.
Figure 2 – Western US year to date (January through April 2026) temperature departure from normal (left) and percent of normal precipitation (right; images from WestWide Drought Tracker, Western Region Climate Center; University of Idaho).
Heat Accumulation:
For the first look at growing degree-days (GDDs) over the western US for 2026, Figure 3 shows most areas of the west seeing above average accumulation during March and April. Central to southern California and into the southwest are running 250-500 GDD above average, while the majority of the PNW is 75-125 GDD above average (Figure 3). Converting the mapped data in Figure 3 to days ahead or days behind normal finds California and Arizona mostly 15-25 days ahead, while the PNW is 5-15 days ahead of normal accumulation amounts (not shown).
For Oregon specifically, heat accumulation (GDD) amounts at four locations that I have tracked for many years in wine regions are above both the 1981-2010 and 1991-2020 climate normals for the month of April 2026 (Figure 4). These locations are all currently tracking either slightly above or close to the same as the 2015 vintage, one of the warmest years in Oregon. These locations are also mostly above the same period in 2025.
Figure 3 – Western US March through April 2026 growing degree-days (image from Climate Impacts Research Consortium, University of Idaho).
Figure 4 – Cumulative growing degree-days (base 50°F, no upper cut-off) for McMinnville, Roseburg, Milton-Freewater, and Medford, Oregon. Comparisons between the current year (2026) and a recent cool year (2010), a recent warm year (2015), and both the 1981-2010 and 1991-2020 climate normals are shown (NCDC preliminary daily data).
Drought Watch:
April precipitation amounts helped alleviate drought in some isolated areas, but were mostly limited across the US. However, the overall broad pattern of drought in the US did not change much from the past couple of months (Figure 5). For the continental US, the overall drought footprint dropped slightly to 76%, with the most extreme drought categories increasing to just under 44%. While April brought some precipitation to the west, the overall drought footprint in the western US increased slightly from last month to just below 92%, with the most extreme categories rising to nearly 44% of the west. In Washington, near average precipitation in April kept the state at 65% in drought, with less than 2% in the most extreme categories of drought. Oregon’s drought footprint increased during April to just under 97% of the state, with the extreme drought categories (severe, extreme, and exceptional) remaining close to 20%. The mountains of northern Idaho and western Montana continue to be one of the drier regions in the northwest, but April precipitation helped lower drought coverage in some areas of each state. Montana continues to show an overall drought footprint close to 94% of the state, with the extreme categories increasing to just over 28% of the state. Idaho saw its overall drought footprint remain nearly 100% of the state, with the most extreme drought categories jumping to nearly 46%. California saw its overall area in drought rise to just over 60%, although there was no area in the more extreme categories of drought at months end (Figure 5).
While the general patterns of the current seasonal drought outlook (Figure 5; right panel) look similar to those of the past few months, some significant differences have become evident. Namely, that much of Texas, the Gulf Coast, and portions of the southeast are now forecast to see drought conditions improve, although the Piedmont and Appalachian mountains into the mid-Atlantic are likely to see drought persist. What is continuing is that large areas of the western US are likely to see drought conditions persist or develop further. For the West Coast states, central to northern California, most of Oregon, and significant portions of Washington, Idaho, and Montana are likely to see drought conditions develop further as we head into our period of seasonal drought. If the additional areas in the western US do transition into drought, then the west will likely see one of its largest footprints for drought since the monitor came out (Figure 5; right panel).
Figure 5 – Current US Drought Monitor and seasonal drought outlook.
ENSO Watch :
The Climate Prediction Center (CPC) has issued its final La Niña advisory as conditions in the Tropical Pacific Ocean show areas across the central Pacific experiencing near-average to warmer than average sea surface temperatures (SSTs) over most of the basin (Figure 6). Tropical Pacific atmospheric conditions also show anomalies that are consistent with the move to full ENSO-neutral. Observations and models are continuing to show a trajectory of SSTs warming over the next few months, with ENSO-neutral favored through June (80% chance), with El Niño likely to emerge by July (61% chance) and remain in place through the end of 2026. Some are even calling this a potentially top-five El Niño. Heading into summer, the overall effect of ENSO on weather conditions for the West Coast continues to weaken but can still be influential in some years. However, the plume of warm water from California to Mexico to Hawaii will likely influence the monsoon season, with the potential for a wetter southwest and possibly California and much of the western US.
Figure 6 – Global sea surface temperatures (°C) for the period ending May 1, 2026 (image from Tropicaltibits.com).
North Pacific Watch:
While the general pattern in SSTs over the North Pacific remains largely the same from the last couple of months, a shift from strong negative values has continued. A broad area of the North Pacific basin remains warmer than average, including along the western North American coast from Alaska south to Baja California and central Mexico and across to Hawaii (Figure 6). The area of cooler than average SSTs in the Gulf of Alaska has shrunk somewhat since last month and could be a strong influence on the summer warmth forecast across the PNW (see the 90-day forecast below). The PDO is still showing negative phase anomalies and will likely continue for the foreseeable future, but its effect tends to lessen heading into the boreal summer, then picks back up in the fall and the transition to winter.
Forecast Periods:
Next 5 Days: Conditions over the west are being influenced by a blocking ridge developing over the Gulf of Alaska, and the PNW and a low shifting south along the California coast. As the low shifts southward, some precipitation is possible in southern Oregon, but most likely from northern to southern California. Flow will be from the southwest, so more humid conditions are likely, while heat builds across the PNW.
6-10 Day (valid May 8-12): Due to the blocking ridge, the PNW is likely to see a much warmer than average and drier than average second week of May. California should stay closer to average, largely due to the low pressure to the southwest that should bring showers over portions of the state as it moves onshore and into the Basin. From the Plains eastward, the rest of the US is forecast for near normal to below normal temperatures as cooler air drops in from Canada. Precipitation amounts will likely be above normal from Texas across the Gulf states and into the southeast, an area that is very dry currently.
8-14 Day (valid May 10-16): Models continue to show the western US dominated by the ridge of high pressure with warmer and drier conditions likely over most of the region. Warmest conditions are likely in the PNW and Basin, with the driest conditions in the PNW. The eastern US will likely continue to see near normal to below normal temperatures through mid-month. Precipitation amounts are forecast to be above normal across the south and up along the eastern seaboard.
30 Day (valid May 1-31): While models for the second half of May are in flux, the overall forecast for the month is for the west to be warmer than average, while the east is likely to see closer to average or below average temperatures (Figure 7). The warmest conditions in May are likely to occur across the PNW into the northern Rockies, while the coolest conditions are forecast for the Great Lakes and the Ohio River valley. In terms of precipitation, the PNW across the northern Rockies and into the Plains are forecast as likely to be drier than average, while most of the rest of the western US has equal chances of being slightly above to slightly below in May. A wetter than average month is most likely in the southwest, where early season monsoon flow may develop, and across Texas and the Gulf Coast region, helping alleviate some of the drought in the region (Figure 5). The rest of the east is forecast for equal chances of above to below normal precipitation for the month (Figure 7).
90 Day (valid May-June-July): The seasonal outlook from May through July has continued to point to a largely warmer than average continental US (Figure 7). Warmer than normal conditions are most likely to be seen in most of the western US, across the south and southeast, and in New England, with the northern Plains and Great Lakes having equal chances. Along with a warmer than average forecast, the western US is also likely to see below average precipitation, especially in the PNW and northern Rockies. The exception is the southwest, where equal chances of above average precipitation are anticipated from the start of what looks like an active monsoon season (Figure 7). For the rest of the country, the Mississippi Valley into the Great Lakes has equal chances of wet to dry season, while the southeast and eastern seaboard are more likely to see a wetter first half of summer.
Figure 7 – Temperature (left panel) and precipitation (right panel) outlooks for the month of May (top panel) and May, June, and July (bottom panel) (Climate Prediction Center, climate.gov).