In December 2025, Washington State flooding was yet another devastating reminder that flood risk in the Pacific Northwest is not only increasing, it is also becoming more complex, more intense, and more interconnected across borders. Just as record-level floodwaters began to recede after days of evacuations and emergency rescues, residents were forced to brace for another powerful storm system.
Back-to-back atmospheric rivers inundated the region, swelling rivers, triggering mudslides, and displacing families across Washington State and into neighboring British Columbia.
What Happened With Washington State Flooding?
An unusually strong atmospheric river system stalled over western Washington, delivering more than a foot of rain in a matter of days. Rivers across the state surged toward dangerous levels, overwhelming floodplains and infrastructure that were already saturated from earlier storms, leading to the significant Washington State flooding event.
The consequences were severe:
- Widespread evacuations across flood-prone communities
- Mudslides that tore through neighborhoods, washing away homes
- Families stranded on rooftops, awaiting rescue
- Critical transportation routes disrupted, including highways and local roads
Flooding was reported across multiple counties, including areas near Burlington, Washington, where entire neighborhoods were submerged. Emergency crews conducted days of water rescues as rain continued to fall.
Why Atmospheric Rivers Are Increasingly Dangerous
Atmospheric rivers are long, narrow corridors in the atmosphere that transport vast amounts of water vapor from the tropics toward higher latitudes. In the Pacific Northwest, these systems typically form during the fall and winter, often carrying moisture from the region near Hawaii, sometimes referred to as the “Pineapple Express.”
Under normal conditions, atmospheric rivers play a critical role in replenishing reservoirs and supporting ecosystems. However, when they become stronger, slower-moving, or occur back-to-back, they can overwhelm watersheds.
Meteorologists noted that this December event was especially potent, fueled by moisture originating even farther west in the Pacific near the Philippines. The result was an extraordinary volume of rainfall delivered over a short period of time, which is far more than many rivers and drainage systems were designed to handle.
Washington State Flooding Into British Columbia
The impacts of this storm system did not stop at the US–Canada border. Washington State flooding extended into British Columbia, where landslides and rising rivers forced additional evacuations and shut down major highways leading into Vancouver. The situation was particularly concerning near the Nooksack and Sumas river systems, which have a long history of cross-border flood impacts.
Although the Nooksack River itself does not cross into Canada, when it floods, excess water spills northward into low-lying areas of Abbotsford, BC. This phenomenon tragically echoed the catastrophic 2021 flood that caused over $1 billion in damages, forced mass evacuations, and severed critical supply routes.
In December 2025, the Nooksack and Sumas rivers once again reached record levels, placing hundreds of properties under evacuation orders in Abbotsford and renewing calls for long-term flood mitigation solutions.
The Infrastructure Gap and Cross-Border Flood Risk
Experts and officials in Canada have repeatedly urged Washington State to invest in flood-prevention infrastructure along the Nooksack River to reduce downstream impacts. While initiatives such as the Snohomish Watershed Resilience Action Plan and the Nooksack and Sumas Transboundary Flood Initiative are steps in the right direction to prevent another devastating Washington State flooding event, researchers argue that progress has been slow.
Flood risk does not recognize political boundaries. As watersheds span borders, so too must planning, investment, and mitigation strategies.
Is Climate Change Making Atmospheric Rivers Worse?
Researchers increasingly point to the human-caused climate crisis as a key driver behind the growing severity of atmospheric rivers. Studies from the US Geological Survey have identified a long-term increase in water vapor transport toward the west coast, linked to warming ocean temperatures. Simply put, warmer air holds more moisture, which means storms have more fuel to release extreme rainfall.
During this December event alone, meteorologists estimated that more than 5 trillion gallons of rain fell across Washington State over seven days. Washington Governor Bob Ferguson underscored the seriousness of the situation during a press briefing:
“The flooding levels we’re looking at are potentially historic in nature. I just want to emphasize how serious the situation is.”
What This Means for Flood Preparedness
The December 2025 Washington State flooding event highlights a sobering reality: flood risk in the Pacific Northwest is escalating, driven by climate change, aging infrastructure, and increasingly powerful storm systems.
For municipalities, businesses, and property owners, this reinforces the importance of:
- Proactive flood risk assessments
- Site-specific flood protection solutions
- Infrastructure upgrades designed for future climate conditions
- Cross-border collaboration and watershed-based planning
At Flood Risk America, we specialize in engineered flood protection solutions designed for real-world conditions, not one-size-fits-all products. From customized flood panels to vulnerability assessments and long-term protection planning, our approach is rooted in understanding how water actually behaves at each site.
If your facility, community, or infrastructure lies in a flood-prone area, now is the time to assess vulnerabilities and invest in solutions tailored to your property. Contact us to speak to a flood expert today.