At 3:30 p.m. on Wednesday, December 10th, residents of Sumas, Washington, situated within the Nooksack River floodplain on the state’s northwest border, received an alarming notification of rising floodwaters. The city’s flood siren blared with a piercing wail, a sound that carried as far north as Abbotsford, British Columbia, signaling an impending crisis. Heeding the urgent warning, most residents quickly gathered their children, pets, and essential belongings, seeking refuge in flood shelters, hotels, or the homes of friends and neighbors. The following morning, the grim reality of the situation became apparent as the only routes into and out of Sumas were submerged. The town and its surrounding areas were submerged under several feet of frigid, silt-laden river water, inflicting damage on hundreds of homes and businesses and leaving a pervasive layer of mud and debris on nearly every surface. Dozens of residents who had not evacuated were perilously stranded on their rooftops, awaiting rescue by U.S. Coast Guard helicopters. By December 12th, as the waters began to recede, the high-water mark was starkly visible everywhere, marked by accumulated trash, leaves, and debris clinging to chain-link fences, and by the muddy streaks left on the sides of nearly every home and vehicle within the inundated zones.

This catastrophic flooding was triggered by two back-to-back atmospheric rivers that relentlessly battered Washington’s west coast in early December, with some locations experiencing as much as 14 inches of rainfall over a 72-hour period at the storms’ peak intensity. The most severely impacted areas were low-lying agricultural regions, while the foothills of the Cascade Range and urban centers such as Seattle, Everett, and Bellingham experienced less severe inundation. The arduous process of recovery has now begun for the affected communities. On December 12th, in the town of Nooksack, located just a short distance from Sumas, volunteers donned thick work gloves, high rubber boots, and waterproof jackets to assist homeowners in the daunting task of cleaning up waterlogged properties. Teams worked to haul sodden carpets and building materials to the street for collection, while others ventured into crawl spaces still submerged in standing water, removing soaked insulation and muddied vapor barriers. Additional volunteers with the Whatcom Long Term Recovery Group, an organization established in the wake of a similarly devastating flood in north Whatcom County in 2021, were stationed at the Nooksack Valley Church. There, they provided assistance in both English and Spanish to residents grappling with insurance claims, state aid applications, and the critical emotional support needed as flood victims re-entered their devastated communities and confronted the daunting question of "what next." As of December 19th, nearly 800 families in Whatcom County had registered for assistance from the recovery group, highlighting the extensive reach of the disaster.

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, the recent series of storms proved to be unusually expansive, unleashing rain as far south as central Oregon. Across Washington State, over 100,000 residents were subjected to evacuation orders as coastal rivers draining the Cascade Range surged to their peak flows on December 11th and 12th. In Skagit County, approximately sixty miles north of Seattle, the communities of Concrete and Hamilton bore the brunt of the deluge. Bridget Moran, a fisheries biologist working in Skagit County who was actively involved in assisting residents with home cleanup, observed 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 narrowly prevented from overwhelming downtown Mount Vernon due to the presence of a protective floodwall. Not all communities, however, benefited from such defenses. In the nearby city of Burlington, 55 homes and sections of the downtown core were inundated on December 12th, necessitating the evacuation of nearly 10,000 residents. Further south, in King County, floodwaters breached a weakened levee on the Lower Green River near the town of Pacific in the early morning of December 16th, prompting officials to evacuate 2,100 residents from the area. The floodwaters ultimately affected approximately 220 homes and around 800 individuals. In Snohomish County, located south of Skagit, a 33-year-old man tragically lost his life after attempting to drive on a closed road and being swept away by floodwaters, marking the first and, to date, only confirmed fatality attributed to the flooding.

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 mountain range. However, the nature of the recent precipitation – arriving predominantly as rain rather than snow, even in the highest reaches of the Cascades – resulted in catastrophic flooding, widespread power outages, and significant mudslides in these regions as well. In Stehekin, near the burn scar of the 2024 Pioneer Fire, residents and businesses suffered substantial damage from landslides and post-fire debris flows in areas where scorched soils and vegetation were more susceptible to destabilization. Further south along the Cascade crest, Stevens Pass sustained such severe damage that its closure is expected to last for several months, while multiple landslides ripped across eastbound Interstate 90, the primary transportation artery through the Cascades. Adding to the woes, Washington experienced a third, albeit slightly colder, atmospheric river during the week of December 15th. The precipitation fell upon watersheds already saturated by the preceding week’s rainfall, triggering further flooding, though thankfully not of the same severity. The wind, however, proved to be more destructive than the water during this subsequent event, causing approximately 380,000 residents across the state to lose electrical power.

The USDA Northwest Climate Hub points to a confluence of increasingly hazardous atmospheric rivers and the overarching impacts of climate change as key factors contributing to these extreme weather events. A warmer atmosphere possesses a greater capacity to hold moisture, while a warming Pacific Ocean serves as a vast reservoir, supplying this increased moisture. Consequently, the duration and intensity of atmospheric river events are escalating. Guillaume Mauger, the Washington State Climatologist, explained that when these factors align, "we’d expect the storms to be more intense." Mauger further elaborated that the extreme danger posed by this particular series of atmospheric rivers stemmed not solely from their individual intensity, but from their rapid succession, leaving little time for natural systems to recover. While researchers are still gathering definitive data to precisely quantify climate change’s role in this specific event, Mauger noted that the unseasonably warm temperatures and the shift towards rain over snow, even at higher elevations, were strong indicators of climate change’s influence. "Atmospheric rivers are warm in general," he 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 throughout Washington are now entering a critical recovery phase, with residents diligently working to salvage belongings and remove water-damaged materials from their homes while simultaneously navigating the complex process of 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 an additional $55 million designated for home repair and recovery efforts. President Donald Trump has approved Governor Ferguson’s request for federal disaster assistance, which enables the Federal Emergency Management Agency (FEMA) to provide support to affected communities and local governments, although it does not directly unlock federal funding for individual victims. A report from the Urban Institute highlights several factors that are likely to complicate the recovery process in many of the hardest-hit areas. These include a high proportion of renters, the prevalence of manufactured homes, and a concerningly low rate of flood insurance coverage. In Whatcom, Skagit, and Snohomish counties, only about a quarter of homes located within the 100-year floodplain carry National Flood Insurance Program policies, which are federally administered programs designed to offer coverage to individuals who might otherwise struggle to obtain insurance due to their vulnerable locations. Shortly after the floodwaters receded on December 12th, the author, working alongside another volunteer, helped a family remove ornaments and lights from their Christmas tree in Nooksack. The tree’s lower branches were caked in mud, and the floor around it was thick with silt. Nearby, other volunteers quietly worked, carrying out couches and children’s toys that were still dripping with river water. Later, standing in the driveway, the author observed volunteers systematically removing sodden items from every home on the block—a scene that would be replicated in thousands of homes across the state in the weeks and months to come. The sheer scale of the devastation was profoundly overwhelming, yet there was little time for contemplation; an immense amount of work remained: removing trim, ripping out flooring, completing mountains of paperwork, rebuilding individual lives, and ultimately, renewing entire communities.