Key Messages from the NOAA Climate Prediction Center
Issued December 9, 2025 and Updated December 11, 2025

Atmospheric Rivers affecting the Pacific Northwest and California into late December

  • A mid-level ridge over the Bering Sea and a downstream trough in the northeastern Pacific increase the likelihood that atmospheric river events will continue affecting the Pacific Northwest and expand southward into central California by December 19. Periods of heavy rain, high-elevation heavy snow, and high winds are most likely from western Washington to central California December 19-22.

  • Given the significant river flooding already impacting western Washington and northwestern Oregon, it seems likely that elevated rivers and saturated soils will linger into late December at least. This will increase the risk of flooding with any heavy precipitation later in the wet season. Landslide vulnerability will remain elevated.

  • (a) The flooding risk is expected to persist into at least late December after expanding into Oregon and northern California by the middle of next week.

  • (a) The highest confidence for heavy precipitation is across southwestern Oregon and northwestern California where a high risk (> 60%) is posted in the Week-2 U.S. Hazards Outlook for December 19-21. A moderate risk (40-60%) is posted from most of western Washington through west-central California for December 19-22.

  • (a) A high risk (>60%) for heavy snow extends from the central Cascades into the northern Sierra Nevada, and a moderate risk (40-60%) is designated for the rest of the Cascades and Sierra Nevada.

  • (a) Enhanced onshore flow supports a moderate risk (40-60%) of high winds for much of the West Coast and northern Interior West, with the highest gusts expected along the coast and at higher elevations.

  • (b) During a wet time of year, there is more than a 60 percent chance of above-normal precipitation from northern California into much of Oregon and northern Nevada. Odds exceed 50 percent from northern Oregon into south-central California.

  • The La Niņa pattern with periods of enhanced onshore flow is favored to persist into the New Year.