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.
The first significant rainfall event in weeks is forecast for coastal British Columbia, Canada, with an atmospheric river expected to bring 20–40 mm (0.8–1.6 inches) to the Lower Mainland and over 50 mm (2 inches) to higher elevations from August 15 to 17, 2025. The rainfall is expected to bring some relief to the region following prolonged wildfire activity that has scorched over 7 000 000 ha (1.8 million acres) across Canada making it the country’s second-worst wildfire season on record.
Wet antecedent soil moisture increased streamflow magnitudes by 2–4.5 times during atmospheric river storms across 122 U.S. West Coast watersheds between 1980 and 2023, according to a new analysis. The study, published in the Journal of Hydrometeorology on June 4, 2025, establishes a nonlinear threshold effect in soil moisture, above which flood response to atmospheric rivers increases sharply.
A recent study from UC San Diego’s Scripps Institution of Oceanography found that ARs were responsible for 70% of years when precipitation deviated from ENSO-based expectations.
A recent study analyzing data from 1980 to 2020 found that atmospheric rivers (ARs), though infrequent, have accounted for up to 70% of extreme snowfall events in East Antarctica since the 1980s, significantly impacting the continent’s ice sheet mass balance.
U.S. weather models, including NCEP and GEFS, project an over 80% chance of a strong atmospheric river making landfall in northern and central California from April 1 to 2, 2025, with additional outlooks from the NWS Climate Prediction Center (CPC) indicating wetter-than-normal conditions and a moderate risk of heavy rain and mountain snow between March 31 and April 4.
An unsettled weather pattern is forecast to continue into next week, with multiple atmospheric rivers expected to bring heavy precipitation to the U.S. West Coast following a March 23 event that caused flooding and a landslide in British Columbia.
Three atmospheric rivers (ARs) are forecast to impact the Pacific Northwest (PNW) from Wednesday, March 19, 2025, into early next week, bringing significant precipitation and potential excessive rainfall to Oregon and Washington.
Two atmospheric rivers (ARs) are forecast to bring winter storm conditions to California, Oregon, and much of the U.S. West Coast starting March 11 and continuing into the weekend. Heavy precipitation and snow accumulations are to expected along with strong winds in the affected regions.
Two atmospheric rivers (ARs) along with a low-pressure system are forecast to bring significant precipitation to much of the U.S. West Coast from March 8 to 14, 2025.
