December 8-11, 2025 Heavy Rainfall and Flooding: Historical Context and a Note on Snow Drought
Event recap
Major flooding impacted western Washington and the eastern Cascades last month. Impacts included numerous washouts and landslides on roadways including a weeks-long shutdown of US-2 and lane closures on I-90.
Early January Climate Outlook
Key Messages
La Niña conditions remain in place, with a 75% chance of neutral conditions by January-March. El Niño conditions are becoming more likely in the extended outlook, with nearly equal chances of neutral or El Niño conditions for the June-August period and minimal chances of La Niña persisting.
Read moreDecember 2025 Climate Summary
December was the warmest December since at least 1895. A considerable warm period through much of the first half of the month boosted monthly average temperatures well above normal. In western Washington, monthly temperatures ran 3-5°F above normal including in Olympia (+4.5°F, fifth warmest on record), SeaTac (+3.2°F, third warmest on record), Hoquiam (+4.2°F, second warmest on record), and Vancouver (+6.2°F, new monthly record).
Read moreDecember 2025 Snowpack and Drought Summary
Key Messages:
Precipitation for the current water year is well-above normal, but not enough to overcome multi-year deficits.
Snowpack remains below normal in the central and southern Cascades, Olympics, Blue Mountains, and the northeastern WA Rockies.
Read moreDecember Notable Weather Events
Key Messages:
A warm atmospheric river event from December 8-11 brought widespread flooding to both western Washington and the eastern slopes of the Cascades. Read more in this article and in this Month’s Climate Matters.
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Counting Every Drop: CoCoRaHS Observer Stories
“I think of CoCoRaHS like the nerves under a person’s skin. Dozens of nerves are useful, but THOUSANDS of nerves give you so much better feedback.”
Every morning, Laurie Pitman takes her border collie, Emma, outside.
Late December Climate Outlook
What’s Next for the Pacific Northwest?
Wetter than normal conditions most likely January-March. Slightly elevated chance of cooler than normal temperatures January-March.
The Climate Prediction Center’s monthly outlook for January 2026 shows good odds (40-50% chance) of wetter than normal conditions across most of the state.
Climate Matters: The CoCoRaHS Rain Gauge Network and a Tale of Two Hydrologic Extremes
On November 14-15, 2021, 4.67” of rain fell at Bellingham International Airport, setting a new record for that location. This storm brought with it the most devastating flood that Whatcom County has seen in decades.
Read moreEarly December Climate Outlook
Key Messages
La Niña conditions remain in place, likely returning to neutral conditions by January-March.
December’s outlook indicates a slight chance of wetter than normal conditions in eastern Washington, but high uncertainty overall.
Read moreNovember and Fall 2025 Climate Summary
Key Messages:
November temperatures were above normal statewide (7th warmest since 1895) with the largest departures from normal across the Columbia Basin and northeastern Washington.
Precipitation was below normal across the Pacific Coast, central and southern Cascades, and southeastern Washington.
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