Early May Climate Outlook

By Jacob Genuise

ENSO-neutral conditions are in place according to the Climate Prediction Center (CPC). Neutral conditions will likely continue through the summer with a 50% chance that neutral conditions persist through August-October 2025. That being said, Neutral or La Niña conditions are still favored for the November 2025 – January 2026 period with only a 20% chance of El Niño conditions during the upcoming winter. ENSO forecasts for the upcoming spring and next winter are notoriously difficult to make at this time of year, so it should become more clear over the next few months whether either La Niña or neutral is favored later in the year. 

As for the upcoming month of May, predictability is generally low. There is a slightly elevated chance of above normal precipitation across northwestern Washington including Puget Sound and the far northern Cascade Mountains. There is a slightly elevated chance (33-40%) that temperatures will be above normal for far eastern Washington in May. This area includes Spokane and Walla Walla. 

There is better agreement in the 3-month outlook for the May-June-July period with increased chances of below normal precipitation and above normal temperatures across the entire state as we head into summer. Below normal precipitation chances are highest (40-50%) across southeastern Washington, while chances of above normal temperatures are highest (40-50%) across far southern Washington including the Tri-Cities area and Snake River Basin. 

Given our below normal snowpack this year and strained reservoir storage, these outlooks raise concerns for increased early season snowmelt and increased irrigation demand as we head into summer 2025.