How much Washington’s snow accumulates during the annual snow season has implications throughout the year. The snowpack is considered a crucial climate-related variable in the Pacific Northwest that affects water supplies for agriculture, fish, hydropower production and recreation.
Washington’s rivers, lakes and reservoirs rely on mountain snow to supply water through the summer. Agriculture and outdoor recreation industries also depend on the snowpack for irrigation and water to support salmon and other fish habitats. The annual snow season typically lasts from October to May.
We’re tracking this season’s snowpack through maps and charts to better understand our water supply in 2024.
CURRENT SNOW SEASON
The 2023-24 snow season had a slow start in the Lower Yakima and the Upper and Lower Columbia basins, which were mostly gone by mid-November. The end of November saw the majority of Washington’s basin below 50% of the 1991-2020 median. Last season saw the end of November with most of the state’s basins well over 100% of the 1991-2020 median, except for the Olympic and Central Columbia basins.
The first 10 days of December saw a series of atmospheric rivers flow into Washington and western Oregon, bringing record-breaking rainfall and above-freezing temperatures which further reduced what little snowpack there was.
Continuing rain from the Pacific along with above-freezing temperatures at the higher elevations saw Dec. 23 with only the Upper Yakima basin at 74% of the 1991-2020 median. Most of Washington’s basins were between 50% and 67%. The Olympic basin was at 28% and the Lower Yakima basin was at 35%. Last season, December ended with most of the state’s basins at or over 110% of the 1991-2020 median. Only the Olympic and North Puget Sound basins were below 100%.
January 2024 has started out with all the state’s basins below 70% of the 1991-2020 median. Most were below 65% until a couple of system from the North Pacific began to move across Washington, bringing colder temperatures and precipitation, in some areas freezing rain, to lower elevations and snow to the passes which brought much of the Western Cascade basins and a couple of the eastern basins to over 80% including the Upper Yakama (86%) and the Lower Snake (83%). Toward the end of January, a series of warm South Pacific atmospheric rivers hit the western Pacific Northwest, bring warmer temperatures and rain. As of Jan. 31, the majority of Washington state’s basins are under 80% of the 1991-2020 median — Lower Columbia (75%) is the highest of the Western Cascade basins. The Olympic basin (33%) is the lowest in the state. The eastern Cascade basins are also dropping — The Upper Yakima (82%) is the only basin over 80% of the 1991-2020 median in Washington. The Lower Yakima and Spokane basins are at 57%. The Lower Snake (79%) has dropped below 80%.
The end of January last year saw most of Washington’s basins at or above 90%, with the Upper Columbia basin the highest (113%) followed by the Lower Columbia basin (104%) and the Lower Snake (101%). North Puget Sound basin was the lowest (79%) followed the Olympic basin (82%).
February 2024 started with above freezing temperatures and rain for most of the state. Oregon and Washington received the very weak end flow of an atmospheric river system that hit Southern California, soaking the Los Angeles and San Diego areas with heavy precipitation. From Feb. 14 through Feb. 19, a cold front moved through from the south which brought snow to Northern Oregon and Washington’s southern basins, but winds from out of the northeast kept the northern basins from receiving any. The end of February saw the West Coast get hit by a large system from out of the North Pacific with cold air, rain and mountain snow falling on Western and Southern Washington basins. As of Feb. 29, Washington’s basins were below 85% of the 1991-2020 media. The Lower Snake basin (84%) was the highest followed by Upper Yakima (83%) and Lower Columbia (79%). The Olympic basin was raised from 34% to 43%, still the lowest followed by the Lower Yakima basin (56%).
Feb. 28, 2023 saw the state’s basins at or above 84% of the 1991-2020 median with the Lower Columbia basin (108%) was the highest followed by the Upper Columbia basin (106%) and Central Puget Sound basin (103%). The Lower Yakima basin (84%) was the lowest followed by the Olympic and North Puget Sound basins at 89%.
The first week of March saw a massive front hit the West Coast and dropped large amounts of snow along the Sierra Mountains between California and Nevada and it brought cold air and snow to Oregon and Washington. All of Washington’s basin saw a much need increase. It was followed by a few localized fronts to Washington and northern Oregon that continued bring cold air and precipitation to lower elevations. As of March 28, the Olympic and North Puget Sound basins were at 60% of the 1991-2020 median. The Lower Columbia basin (88%) was the highest followed by the Lower Snake-Walla Walla basin (87%) and the Lower Pend basin (80%).
March 2023 ended with all but two of Washington basin’s at or above 90% of the 1991-2020 median. The highest was the Lower Snake-Walla Walla basin (117%) followed by Lower Columbia basin (114%) and Central Puget Sound basin (107%). The lowest was the North Puget Sound basin (84%) followed by the Olympic basin (89%).
The month of April and into the first week of May saw some weak cold fronts bring colder temperatures with some snow to the higher elevations and even some hail and rain to lower elevations. But clear skies and warm daytime highs brought in by high pressure systems, saw most of Washington’s basin through at or below 70% of the the 1991-2020 median through to the end of April. The lowest was the Lower Yakima (48%) and the highest was the Lower Columbia (88%), the only basin above 80%.
Last season, April ended with all but the North Puget Sound basin (86%) at or above 90%. The Lower Snake-Walla Walla basin (128%) was the highest. May of 2023 continued the trend with all but two basins at or above 90%. The North Puget Sound and Central Columbia (87%) were the lowest on May 3 with the Lower Snake-Walla Walla basin (139%) the highest followed by the Lower Columbia basin (127%).
MAY SNOWPACK
APRIL SNOWPACK
MARCH SNOWPACK
Comparing current snowpack to the past season for select basins at the end of the day. The annual snow season lasts from October to May.
FEBRUARY SNOWPACK
Comparing snowpack to the past seasons for select basins on the first reading of the day. The annual snow season lasts from October to May.
JANUARY SNOWPACK
Comparing snowpack to the past seasons for select basins on the first reading of the day. The annual snow season lasts from October to May.
DECEMBER SNOWPACK
Comparing snowpack to the past seasons for select basins on the first reading of the day. The annual snow season lasts from October to May.
NOVEMBER SNOWPACK
Comparing snowpack to the past seasons for select basins on the first reading of the day. The annual snow season lasts from October to May.
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CURRENT SNOWFALLS AT SNOQUALMIE, STEVENS AND WHITE PASSES
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FIRST SNOWFALL AT SNOQUALMIE AND STEVENS PASSES
Historically, Stevens Pass gets its first snow before Snoqualmie Pass. This snow season, Stevens Pass had 7 inches of snow arrive on Oct. 25. Snoqualmie Pass received 4 inches of snow on Oct. 26. The 2022-23 snow season started with Stevens Pass at 1 inch on Oct. 24 and Snoqualmie Pass at 4 inches on Oct. 26.
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PAST SNOW LEVELS
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