Snohomish County Disaster Risk
Snohomish County, Washington
FEMA Risk Rating
Relatively High
National Percentile
98th
of 3,144 counties
State Rank
#3
of 39 (1 = highest risk)
Flood Risk
96th
percentile
Hazard Risk Breakdown
Flood
River, coastal, and surface flooding risk
Relatively High
Higher than 96% of US counties
Wildfire
Wildland and wildland-urban interface fire risk
Relatively Low
Higher than 61% of US counties
Tornado
Tornado and severe thunderstorm risk
Very Low
Higher than 39% of US counties
Earthquake
Seismic activity and ground shaking risk
Relatively High
Higher than 99% of US counties
Risk Overview
About Natural Disaster Risk in Snohomish County, Washington
Snohomish County's disaster risk is relatively high
Snohomish County scores 97.87 on the composite risk scale, far exceeding Washington's state average of 70.01 and placing it in the relatively high risk category nationally. This means Snohomish residents face more frequent and severe natural hazards than most American counties. The county's large population and geography create compounded disaster exposure across multiple interconnected hazard types.
Highest-risk county in Washington
Snohomish County ranks first statewide for overall disaster risk, with a 97.87 score that exceeds Pierce County (98.54) and Pacific County (92.75). Snohomish's scores are exceptional across three hazard types: earthquake (99.33), flood (95.74), and tornado (38.80), creating a uniquely complex risk environment. Only Snohomish and Pierce counties exceed 97 on Washington's composite risk scale.
Most hazardous Puget Sound location
Snohomish County's 97.87 score is slightly higher than Pierce County (98.54) despite nearly identical earthquake and flood profiles, reflecting Snohomish's slightly higher tornado risk (38.80 vs Pierce's 41.22). Both counties share similar geographic exposure to the Cascadia Subduction Zone and river systems, making them Washington's two riskiest metropolitan areas. Neighboring San Juan County (35.37) faces dramatically less overall hazard exposure due to its island location.
Earthquakes, floods, and tornadoes prevail
Earthquake risk (99.33) is Snohomish County's dominant threat, with the Cascadia Subduction Zone directly beneath the county creating potential for catastrophic ground shaking and tsunami hazards. Flood risk (95.74) affects river valleys, Puget Sound lowlands, and urban stormwater systems, particularly during winter storms and spring snowmelt. Tornado risk (38.80) is surprisingly significant for western Washington, exceeding many Midwest communities and requiring storm preparedness alongside seismic and flood measures.
Comprehensive multi-hazard insurance essential
Snohomish County homeowners must secure earthquake insurance (separate from standard policies) and flood insurance through the National Flood Insurance Program if in a mapped flood zone—the county's 95.74 flood risk makes this mandatory. Review your property's tsunami hazard zone and establish multiple evacuation routes, as seismic events could trigger coastal inundation. Consider reinforcing your home's seismic stability through foundation bolting and soft-story retrofits, and establish a basement safe room for tornado warnings.
Source: FEMA National Risk Index · Narrative reviewed by Evan Brooks, Data Editor
Preparedness Guide
What to Prepare for in Snohomish County
Top Hazards by Exposure
Source: FEMA National Risk Index v1.19.0 · Percentiles are national (3,144 counties)
Risk Advisory: Snohomish County
Risk Verdict
At the 98th percentile nationally, Snohomish County is among the more hazard-exposed counties in the United States. Proactive preparedness — not reactive response — is key to managing life in one of the country's higher-risk counties; Snohomish County residents should plan accordingly.
Hazard Breakdown
Earthquake risk is Snohomish County's dominant natural hazard, ranked at the 99th percentile nationally under FEMA's National Risk Index. Flood ranks second at the 96th percentile nationally. Additional tracked hazards include wildfire (61th percentile), tornado (39th percentile).
Preparedness Context
At the 99th percentile nationally for earthquake exposure, Snohomish County households benefit from practicing Drop, Cover, and Hold On — the protocol that minimizes injury during shaking. Getting under a sturdy table or desk and holding on until shaking stops is the key action. Alongside earthquake exposure, Snohomish County's flood risk at the 96th percentile nationally reinforces the value of maintaining a household emergency supply cache usable for multiple hazard scenarios. Building age matters for earthquake risk in Snohomish County: structures built before local seismic code adoption are statistically more vulnerable. Contacting the local building department about retrofit programs can reveal whether your structure qualifies for mitigation assistance.
Regional Context
At 27.9 points above the Washington state average, Snohomish County carries meaningfully higher natural disaster exposure than a typical Washington county.
Is your household prepared for Snohomish County's hazards?
Review FEMA's county-specific preparedness checklists and emergency planning guides.
Frequently Asked Questions
What is the natural disaster risk in Snohomish County, WA?
What types of natural hazards affect Snohomish County?
How does Snohomish County risk compare to the Washington average?
Is Snohomish County at risk for earthquake?
How is natural disaster risk measured?
Why is Snohomish County higher risk than average?
Data Source
Risk data sourced from the FEMA National Risk Index (NRI). Risk scores are relative rankings (0–100) across all US counties — not absolute risk measures. Higher scores indicate higher relative risk compared to other counties.
Disclaimer: This data is informational only. It is not financial, insurance, or legal advice. Always consult a qualified professional before making insurance or real estate decisions.