Beginning on December 8, 2025, a series of severe floods impacted rivers and lowlands in the Pacific Northwest, particularly Western Washington in the United States and the Fraser Valley in British Columbia, Canada. The floods were triggered by an atmospheric river that was among the strongest and longest-lasting in the history of the Puget Sound region. Up to 10 inches (25cm) of rain is expected to fall in the Cascade Range due to the storm system and a total of 5 trillion gallons (19 trillion liters) within a week-long period.[1][2]
A state of emergency was declared by Washington governor Bob Ferguson on December 10 along with an order to deploy the Washington National Guard to prepare for disaster response.[3] An estimated 100,000 people in Washington are within areas with evacuation orders due to the expected impact of the floods.[4][5][6] A local state of emergency was declared in several areas of British Columbia near the Fraser River.[7]
Meteorological synopsis
Upper level weather analysis showing a strong jet stream, which carried the atmospheric river, moving into the Pacific Northwest on December 9.
A persistent high pressure system near California blocked inbound weather systems from progressing southward. This caused the cold fronts associated with multiple low pressure systems to stall leading to the formation of an extreme atmospheric river aimed at the Pacific Northwest beginning December 8.[8] For much of the event, the main moisture plume was aimed over Western Washington but it oscillated from Northwest Oregon to the Lower Mainland of British Columbia.[9]
Forecasters at the Center for Western Weather and Water Extremes forecasted the system to reach category 5 on the atmospheric river intensity scale as early as December 5, indicating a high risk of widespread flooding.[10] To improve weather forecasts, the National Weather Service with support from Air Force Reserve 53rd Weather Reconnaissance Squadron sent multiple hurricane hunter flights to collect data from the storm system.[11]
The source region of the moisture plume lead to very warm temperatures. Snow levels rose to above 7,000ft (2,100m) above sea level in the impacted region.[12] Snowpack was already near record lows leading up to the event but what snow was present in the mountains rapidly melted due to heavy rain.[13] Temperatures on December 10 soared to record highs with Yakima, Washington recording 72°F (22°C).[14]
While they don't occur every year, strong atmospheric rivers are common in the Pacific Northwest in the fall and winter. Other major floods from such events include the 2024 British Columbia floods and the 2021 Pacific Northwest floods.[16][17] On the whole, atmospheric rivers account for 30–50% of the annual precipitation observed in the Pacific Northwest though the majority of atmospheric river events are weaker.[18]Atmospheric rivers are likely to increase in frequency and severity due to human-caused climate change.[19]
Over 300 Washington National Guard members were deployed to assist with the flood response which had impacts around the Cowlitz and Skagit rivers.[20]
Some areas had over 7 inches (180mm) rainfall over 48 hours as of December 9.[21] A further 4 to 8 inches (100 to 200mm) was expected at higher elevations on December 10 and 11.[22] In some places the rainfall broke records, such as Olympia Regional Airport, which recorded 3.03 inches (77mm) on December 8.[23]
On Wednesday, AccuWeather forecasted that "nearly every small stream and short-run river in western Washington and Oregon will reach at least minor to moderate flood stage."[24] Water height gauges broke records for the Yakima River at Easton on Wednesday[24] and Grays River near Rosburg on Monday.[23] The Snohomish River, Skagit River, and Cedar River broke all-time flood records on December 11, while other rivers including the Skykomish, the Stillaguamish and the Snoqualmie fell just short of record highs.[25][26] The Skagit River is expected to reach a record-high crest of 42 feet (13m) near Mount Vernon on December 11. On December 10, more than 75,000 people were ordered by Skagit County officials to evacuate, including all of Burlington and parts of Mount Vernon.[27] Many roads were rendered impassible due to floodwaters.[28] Several major highways were closed due to flooding and mudslides, leaving "almost all routes east from the Pacific Northwest" unusable.[29][30]
In Kent, both property owners and the city were hastily erecting flood barriers on December 10 as the Green River exceeded its banks adjacent to State Route 181.[32] The Green River flooding also closed some roads in Auburn and Sumner.[33]
A section of Interstate 90 near North Bend was closed on December 9 due to a mudslide that covered the road with debris; it reopened the following day.[34] The 50-mile (80km) section of U.S. Route 2 that crosses the Cascade Range at Stevens Pass was closed on December 10 between Index and Coles Corner. Several landslides had covered the highway in debris that are planned to be cleared.[35] Several sections of U.S. Route 12 in Lewis County were closed due to flooding, which isolated the town of Randle. Amtrak announced the suspension of its trains between Seattle and Vancouver due to the Skagit River's expected flood level.[4] The Sumas Border Crossing was closed to southbound commercial traffic to allow local residents to use roads to evacuate.[36] Later on, Sumas, as well as nearby Nooksack and Everson were flooded.[37]
In Lewis County, the communities of Randle and Packwood suffered severe flooding when the Cowlitz River "double-crested". U.S. Route 12 was underwater and several people were evacuated along the Cowlitz.[38][39] A 15-mile (24km) stretch of US 12, east of Morton, was closed due to water and debris on the highway.[40]Interstate 5 ramps in Napavine were temporarily closed;[41] other roads in the community were overwhelmed and several people were rescued after their vehicles were submerged in the flood waters.[38] Portions of both SR 6 and SR 508 in the county were closed due to floodwaters over the roads.[41] Highway 20 was closed due to mudslides near Winthrop and remained closed on 14 December. Although Highway 90 and 97 reopened after mudslides were cleared, Highway 2 and 12 need substantial repairs to be completed before they can fully reopen.[42]
On 11 December the small town of Stehekin lost its water treatment plant and the road from the ferry dock to other parts of the town. It was also out of power after a massive torrent of mud and debris flooded down two small creeks.[43] Due to flooding on the Wenatchee River, Leavenworth was partially flooded and lost power.[44]
Rainfall is occurring heavily in Abbotsford and Chilliwack in the Fraser Valley, expected to range around 80 to 110 millimetres.[47] As of December 10, Metro Vancouver isn't as heavily affected by the atmospheric river as the Fraser Valley, but this is still developing.[48]
On December 10, all highways connecting the Lower Mainland to the interior of the province were closed to due flooding, rock falling, and avalanche risks.[49] Only BC Ferries and highways south to the United States were operational.[50]
Semá:th Elementary of School District 34 (Abbotsford) and School District 78 (Hope, Harrison Hot Springs, Agassiz) schools were cancelled Thursday, December 11 due to the flooding.[51] Later that night, Chilliwack School District 33 stated that schools would be cancelled for staff and students on December 12 due to floods creating unsafe and unpredictable travel conditions.[52]
Flooding led to a State of Local Emergency being declared in portions of the Fraser Valley, Abbotsford and Chilliwack are the most affected.[53]Electoral Area E, just south of Chilliwack, a dozen properties were ordered to evacuate.[54]Highways 1, 7, and 99 were shut down Wednesday night as the storm intensified.[55] Clayburn Village and Sumas Prairie in Abbotsford were ordered to evacuate, leading to over 370 properties affected.[56]
Vancouver Island
On Vancouver Island, the atmospheric river is expected to range around 40 to 75 millimetres in the Victoria area, with western Vancouver Island expected to reach 110 millimetres of rain.[57] The BC River Forecast centre issued a High Streamflow Advisory warning for the region.[58]
Montana
Between December 6 and December 11, 12–13 inches (300–330mm) of rain fell at the Bear Mountain SNOTEL site on the Idaho-Montana border. In the 24 hours ending on December 11, 5–6.5 inches (130–170mm) of rain had fallen and the Missoula office of the National Weather Service ranked that as the third wettest 24-hour period in 44 years of records.[59]
Starting on December 8, the Fisher and Yaak Rivers reached flood stages. A flooding disaster was declared by Montana's Governor, Greg Gianforte on December 11 for the northwestern corner of the state. The declaration said that Lincoln, Sanders, and Flathead Counties had enacted emergency or disaster declarations.[60]
On December 11, the Lincoln County Health Department posted a boil water order for the city of Libby on their Facebook page. The order said it was "precautionary but essential to protect public health during flood-related impacts to the water system."[61]
National Weather Service meteorologist, Dan Borsum told the Montana Free Press the weather pattern was "unusual" for mid-December.[62]
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