At 3:30 p.m. on Wednesday, December 10th, the residents of Sumas, Washington, situated within the Nooksack River floodplain on the state’s northwest border, received an urgent warning of rising floodwaters. The city’s flood alarm blared with an unsettling wail, a sound that carried as far north as Abbotsford, British Columbia, prompting most residents to heed the alert. They quickly gathered their children, pets, and essential belongings, seeking refuge in flood shelters, hotels, or the homes of friends in higher ground. By the following morning, the sole access routes into and out of Sumas were submerged, with the town and its surroundings inundated by several feet of frigid, sediment-laden river water that inflicted damage on hundreds of homes and businesses, leaving a thin layer of silt on nearly every surface. Dozens of individuals who had not evacuated were rescued from their rooftops by a U.S. Coast Guard helicopter. As the waters began to recede on December 12th, the high-water mark was starkly visible across the landscape, marked by debris, leaves, and the tell-tale muddy streaks adorning fences, homes, and vehicles throughout the affected areas.

The Pacific Northwest was battered by two consecutive atmospheric rivers in early December, with some locations recording up to 14 inches of rain over a 72-hour period at the peak of the storms. While low-lying agricultural regions bore the brunt of the flooding, the foothills of the Cascade Range and urban centers like Seattle, Everett, and Bellingham experienced less severe impacts. The arduous process of recovery has now commenced. On December 12th, in the town of Nooksack, located just a short distance from Sumas, the scene was one of widespread devastation. Donning thick work gloves, high rubber boots, and waterproof jackets, I joined a contingent of volunteers to assist homeowners with the daunting task of clearing waterlogged debris. Together, we hauled sodden carpets and building materials to the curb for collection, while others ventured into crawl spaces still submerged in standing water, diligently removing soaked insulation and muddied vapor barriers. Additional volunteers from the Whatcom Long Term Recovery Group, an organization established in the wake of similar devastating floods in north Whatcom County in 2021, were stationed at the Nooksack Valley Church. There, they provided crucial support to residents in both English and Spanish, assisting with insurance claims, state aid applications, and offering much-needed emotional solace as flood victims navigated the re-entry into their devastated communities and grappled with the uncertainty of what lay ahead. As of December 19th, nearly 800 families in Whatcom County had sought assistance from the recovery group.

Atmospheric rivers, defined as narrow bands of concentrated water vapor originating over the warm waters of the Pacific Ocean, are a regular feature of the West Coast’s climate, delivering substantial precipitation. However, this particular series of storms exhibited an unusual breadth, extending its reach as far south as central Oregon. More than 100,000 residents across Washington faced evacuation orders as coastal rivers draining the Cascade Range reached their peak flows on December 11th and 12th. In Skagit County, located sixty miles north of Seattle, the communities of Concrete and Hamilton were particularly hard-hit; Bridget Moran, a fisheries biologist working in Skagit County who was actively involved in assisting residents with home cleanups, noted that the high-water mark in some Hamilton homes exceeded six feet. Further downstream, the Skagit River, flowing at a record-breaking 37.7 feet, was prevented from breaching downtown Mount Vernon only by the presence of a protective floodwall.

Not all communities were as fortunate. In nearby Burlington, 55 homes and sections of the downtown core were inundated on December 12th, necessitating the evacuation of the town’s nearly 10,000 residents. In south King County, floodwaters breached an already weakened levee along the Lower Green River near the town of Pacific in the early morning of December 16th, triggering officials to evacuate 2,100 residents from the area. Ultimately, the floodwaters impacted approximately 220 homes and around 800 individuals. In Snohomish County, south of Skagit, a 33-year-old man lost his life after attempting to drive through a closed road and being swept away by the floodwaters, marking the first and only confirmed fatality attributed to the flooding thus far.

Communities situated at higher altitudes in the East Cascades, such as Naches, Leavenworth, and Methow, typically experience colder and drier conditions compared to areas west of the Cascades. However, the nature of the precipitation during these storms, with the majority arriving as rain rather than snow even in the highest reaches of the Cascades, led to catastrophic flooding, widespread power outages, and numerous landslides in these regions as well. In Stehekin, near the burn scar of the 2024 Pioneer Fire, residents and businesses suffered significant damage from landslides and post-fire debris flows in areas where scorched soils and vegetation are more susceptible to destabilization. Further south along the Cascade crest, Stevens Pass sustained such extensive damage that its closure is expected to last for months, while multiple landslides obstructed eastbound Interstate 90, a critical transportation artery through the Cascades. Washington was subsequently impacted by a third, albeit colder, atmospheric river during the week of December 15th. The precipitation, falling on watersheds already saturated from the preceding week’s rainfall, caused further flooding, though of a lesser magnitude. However, the accompanying winds proved to be more destructive than the water, leaving approximately 380,000 people across the state without power.

The USDA Northwest Climate Hub points to the escalating frequency and intensity of atmospheric rivers, coupled with the broader impacts of climate change, as key contributing factors. A warmer atmosphere possesses a greater capacity to hold moisture, while a warming Pacific Ocean serves as a more abundant source of this moisture, leading to an increase in both the duration and strength of atmospheric river events. Guillaume Mauger, Washington state climatologist, explained that when these elements converge, "we’d expect the storms to be more intense." Mauger emphasized that the extreme danger posed by this particular series of atmospheric rivers stemmed not solely from their individual intensity but also from their rapid succession. He was careful to note that researchers still require more comprehensive data to fully understand the precise influence of climate change on this specific storm event. However, he highlighted that the unseasonably warm temperatures and the shift in precipitation from snow to rain, even at higher elevations, likely indicated climate change’s role. "Atmospheric rivers are warm in general," Mauger stated, "But if this event had happened in 1950, the snowline wouldn’t have been quite so high. That’s the big effect: that it’s just less snow and more rain."

Communities across Washington are now transitioning into the recovery phase, with residents engaged in the difficult process of salvaging belongings and removing water-damaged materials from their homes while simultaneously seeking financial assistance. Washington Governor Bob Ferguson has allocated $3.5 million in emergency funding to aid flood victims and has proposed a supplemental budget that includes $55 million designated for home repair and recovery efforts. President Donald Trump has approved Governor Ferguson’s request for federal disaster assistance, which authorizes the Federal Emergency Management Agency (FEMA) to provide support to communities and local governments, although it does not directly unlock federal funding for individual victims.

Several factors are likely to complicate the recovery process in many of the affected areas, including a high proportion of renters, the prevalence of manufactured homes, and a significant lack of flood insurance, according to a report by the Urban Institute. Data indicates that only about a quarter of homes situated within the 100-year floodplain in Whatcom, Skagit, and Snohomish counties are covered by flood insurance through the National Flood Insurance Program, a federally administered policy designed to assist individuals who might otherwise struggle to obtain coverage due to their low-lying locations.

Shortly after the floodwaters receded on December 12th, I joined another volunteer in Nooksack to help a family remove ornaments and lights from their Christmas tree. The tree’s lower branches were coated in mud, and the floor surrounding it was thick with silt. Elsewhere on the block, other volunteers worked quietly, carrying out couches and children’s toys still dripping with river water. Later, standing in the driveway, I observed volunteers methodically clearing wet items from every home on the street – a scene that would be replicated in thousands of residences across the state in the weeks and months to come. The sheer scale of the devastation was overwhelming, yet there was little time for contemplation; an immense amount of work remained, from removing trim and ripping out flooring to completing crucial paperwork, rebuilding lives, and ultimately, renewing entire communities.