Sumas, Washington, a community nestled within the Nooksack River floodplain, received a stark warning of rising floodwaters at 3:30 p.m. on Wednesday, December 10th. The city’s flood alarm blared, its unsettling wail audible as far north as Abbotsford, British Columbia, prompting most residents to heed the alert. They quickly gathered children, pets, and essential belongings, seeking refuge in flood shelters, hotels, or the homes of friends and neighbors. By the following morning, the sole access routes into Sumas were submerged, leaving the town and its surrounding areas inundated by several feet of frigid, silt-laden river water. This deluge wreaked havoc on hundreds of homes and businesses, leaving a thin layer of mud and debris on nearly every surface. Those who did not evacuate faced perilous situations, with dozens ultimately rescued from their rooftops by U.S. Coast Guard helicopters. As the waters finally receded on December 12th, the high-water mark served as a grim testament to the storm’s ferocity, evidenced by the accumulation of trash, leaves, and debris clinging to chain-link fences and the muddy streaks marring homes and vehicles throughout the affected zone.

The devastating events were precipitated by two consecutive atmospheric rivers that lashed the west coast of Washington in early December, with some locations recording up to 14 inches of rain within a 72-hour period at the storms’ zenith. While low-lying agricultural regions bore the brunt of the impact, the foothills of the Cascade Range and urban centers like Seattle, Everett, and Bellingham experienced less severe consequences. The arduous process of recovery has now begun. On December 12th, in the town of Nooksack, situated just downriver from Sumas, volunteers donned heavy-duty gloves, tall rubber boots, and waterproof jackets to assist homeowners in the sodden task of cleanup. Together, they hauled waterlogged carpets and building materials to the curb for collection, while others ventured into partially submerged crawl spaces, extracting soaked insulation and muddied vapor barriers. Additional volunteers, part of 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 assistance in both English and Spanish, helping residents navigate insurance claims and state aid applications, while also offering crucial emotional support as individuals returned to their devastated community, grappling with the overwhelming question of "what next?" As of December 19th, nearly 800 families in Whatcom County had registered for assistance from the recovery group.

Atmospheric rivers, characterized as narrow bands of concentrated water vapor originating from the warm waters of the Pacific Ocean, are a regular feature along the West Coast, delivering significant precipitation. However, the early December storms proved exceptional in their breadth, extending their reach as far south as central Oregon. Across Washington, more than 100,000 residents faced evacuation orders as coastal rivers draining the Cascade Range surged to their peak flows on December 11th and 12th. In Skagit County, approximately 60 miles north of Seattle, the communities of Concrete and Hamilton were particularly hard-hit. Bridget Moran, a fisheries biologist working in Skagit County who joined the cleanup efforts, 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 prevented from breaching the downtown area of 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, compelling the evacuation of the town’s nearly 10,000 residents. In south King County, floodwaters breached an already compromised levee on the Lower Green River near the town of Pacific in the early morning hours of December 16th, triggering evacuation orders for 2,100 residents. Ultimately, approximately 220 homes and around 800 residents were impacted by these floodwaters. Snohomish County, south of Skagit, reported the first and only confirmed fatality attributed to the flooding thus far: a 33-year-old man who was swept away by floodwaters while attempting to drive on a closed road.

Communities situated at higher altitudes in the East Cascades, such as Naches, Leavenworth, and Methow, typically experience colder and drier conditions compared to those west of the mountain range. However, the unusually warm temperatures associated with this weather system meant that the majority of precipitation fell as rain, even in the highest elevations of the Cascades. This resulted in catastrophic flooding, widespread power outages, and significant mudslides in these areas 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 recently burned areas, where scorched soils and vegetation are inherently more susceptible to destabilization. Further south along the Cascade crest, Stevens Pass sustained such severe damage that its closure is expected to last for months, while multiple landslides rendered the eastbound lanes of I-90, the primary east-west artery through the Cascades, impassable. Washington experienced a third, albeit slightly colder, atmospheric river during the week of December 15th. This additional precipitation, falling on watersheds already saturated from the preceding storms, led to further flooding, though generally less severe than the initial events. However, the accompanying high winds proved more destructive than the water, leaving approximately 380,000 people across the state without power.

The USDA Northwest Climate Hub points to a confluence of factors, including increasingly hazardous atmospheric rivers and the broader impacts of climate change, as contributing to these extreme weather events. A warmer atmosphere possesses a greater capacity to hold moisture, and a warming Pacific Ocean provides an amplified source of this moisture, leading to an increase in both the duration and intensity of atmospheric river events. Guillaume Mauger, Washington state climatologist, explained that these combined factors predict more intense storms. Mauger emphasized that the danger posed by this particular series of atmospheric rivers was not solely due to their individual strength but also their rapid succession. While acknowledging that researchers still require definitive data to precisely link climate change to this specific event, Mauger noted that the unseasonably warm temperatures and the shift from snow to rain as the dominant form of precipitation 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 across Washington are now transitioning into the recovery phase, with residents working to salvage belongings and remove water-damaged materials from their homes while simultaneously seeking financial assistance. Washington Governor Jay Inslee has allocated $3.5 million in emergency funding to aid flood victims and has put forth a supplemental budget that includes $55 million designated for home repair and recovery initiatives. President Joe Biden approved Inslee’s request for federal disaster assistance, which enables 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. Reports from the Urban Institute suggest that recovery in many impacted areas will be particularly challenging due to several key factors: a high proportion of renters, a prevalence of manufactured homes, and a widespread lack of flood insurance. The report indicates that only about a quarter of homes situated within the 100-year floodplain in Whatcom, Skagit, and Snohomish counties are covered by the National Flood Insurance Program, a federally administered policy designed for properties in high-risk flood zones.

Shortly after the floodwaters receded on December 12th, the author, alongside another volunteer, assisted a family in Nooksack by removing ornaments and lights from their Christmas tree, its lower branches coated in mud and the surrounding floor thick with silt. Other volunteers worked quietly nearby, carrying out couches and children’s toys still dripping with river water. Later, standing in the driveway, the sight of volunteers methodically removing waterlogged items from every home on the block was a poignant reminder of the immense task that lay ahead for thousands of households across the state in the coming weeks and months. The sheer scale of the devastation was overwhelming, yet the urgency of the situation left little room for dwelling on it. There remained a vast amount of work to be done: removing trim, tearing out flooring, completing extensive paperwork, rebuilding lives, and ultimately, renewing entire communities.