May 10, 2023
As the state's lead agency for water supplies, we pay close attention to multiple data sources and monitor them closely. The Office of the Washington State Climatologist serves as a credible and expert source of climate and weather information for the state. Their monthly newsletter reviews the previous month’s data and provides an outlook for the coming weeks.
Despite some record-breaking daily high temperatures on the 28th and 29th, April’s temperatures averaged at below normal statewide (-2.2o F below the 1991-2020 normal). Although it varied in areas around the state, monthly precipitation averages were generally above normal in April (0.9” above normal). SeaTac Airport and Rosalia, WA in the southeast corner of the state, each had daily record snowfall on April 4 (trace and 4” respectively).
The cooler and wetter weather contributed to late-season mountain snowpack improvements, with nearly every basin ending with near-average to above average seasonal accumulation. The exception, with only 88% of median on May 1, was the North Puget Sound basin. In addition, with the unusually warm days at the end of the month, some locations are already experiencing quicker than normal snowmelt.
Find details as well as a review of Winter 2022-2023, and a climate summary and outlook in the May edition of the State Climatologist’s Newsletter.