Two successive atmospheric river pulses are affecting the Pacific Northwest this week, delivering multi-day heavy rainfall and flooding risk across western Washington and northwestern Oregon. The first made landfall early December 9, and a stronger second pulse is forecast to arrive late December 9–early December 10, maintaining high integrated vapor transport and major flood potential through December 11.
A major atmospheric river (AR4–AR5 possible) is forecast to make landfall over the Pacific Northwest early Monday, December 8, 2025, and persist through Wednesday, December 10, bringing multiple days of heavy rain and elevated snow levels. Ensemble guidance shows ~70–80% of members reaching at least AR4 in southern coastal Washington, with ~20–30% indicating AR5, raising the risk of widespread riverine flooding.
Three atmospheric rivers (ARs) are forecast to make landfall over the Pacific Northwest (PNW) through December 10, 2025, producing prolonged precipitation and high moisture transport across western Washington and Oregon.
Four back-to-back atmospheric rivers are forecast to make landfall along the U.S. West Coast between November 3 and November 9, 2025. Heavy rainfall totals of 76–130 mm (3–5 inches), with isolated amounts up to 177 mm (7 inches), could lead to localized flooding in parts of northern California and Washington State throughout the week.
Two atmospheric rivers are forecast to hit the Pacific Northwest and northern California, starting late Thursday, October 23, 2025. The systems are forecast to bring in heavy rainfall of over 130 mm (5 inches) along with mountain snow across Washington, Oregon, and northern California.
The Pacific Northwest will see back-to-back atmospheric rivers (ARs) beginning late Thursday, October 23, 2025, bringing significant precipitation and unsettled weather conditions through the end of October.The Weather Prediction Center has issued a Marginal Risk of excessive rainfall for coastal areas of Washington, Oregon, and northern California as the AR approaches.
A powerful atmospheric river is forecast to impact the western United States between October 25 and 31, 2025, bringing heavy rainfall, mountain snow, and high winds from Northern California to Washington.
An atmospheric river (AR) is expected to reach the Pacific Northwest (PNW) on Saturday, October 18, 2025, bringing heavy rain and elevated freezing levels above 2 400 m (8 000 feet) before lowering as the system moves east. 25–100 mm (1–4 inches) of rainfall is forecast over coastal Washington and Oregon, with orographic enhancement expected on the Olympic Peninsula and Northern Cascades.
An atmospheric river (AR) with moderate-to-strong integrated vapor transport (IVT) exceeding 500 kg m⁻¹ s⁻¹ is forecast to make landfall over the Pacific Northwest and southern British Columbia on the evening of August 14, 2025, bringing sustained AR conditions for about 24 hours and significant precipitation through August 16.
A Pacific storm and atmospheric river will impact the Pacific Northwest states and northern Rockies this weekend, bringing locally heavy low-elevation rain and heavy high-elevation snow in the mountains. By Sunday over the Interior Northwest, rain combined with snowmelt will increase the risk of flood hazards.
