Snohomish County, Washington Natural Disaster Risk
FEMA National Risk Index assessment · WA
HighComposite Risk Score
National percentile: 98th
Snohomish County faces high composite natural disaster risk (NRI Risk Index score 97.9, 98th national percentile), driven primarily by landslide and earthquake exposure. Expected annual loss across all 18 hazard types is $409M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Snohomish County carries a high composite natural disaster risk, with a National Risk Index score of 97.9 out of 100 — placing it in the 98th national percentile and in the upper tier of natural-disaster risk nationally. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in landslide (downhill movement of rock, soil, and debris on unstable slopes) at Very High risk — $25M in expected annual loss and about 4.12 events per year; earthquake (ground shaking from sudden movement along geologic faults) at High risk — $247M in expected annual loss and about 0.04 events per year; and ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Very High risk — $4M in expected annual loss and about 0.45 events per year. Across all hazards, FEMA estimates $409M in expected annual loss for a population of 828K.
Beyond physical exposure, Snohomish County has a very low social vulnerability rating (how susceptible the population is to harm) and a high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
The county's disaster history tells the same story: Snohomish County has received 37 federal disaster declarations since 1964, including 15 for severe storm events and 13 for flood events. The most recent was Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides (flood), declared in April 2026.
Among 39 Washington counties, Snohomish County ranks #3 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Landslide | Very High | 4.12 / yr | $25M |
| Earthquake | High | 0.04 / yr | $247M |
| Ice Storm | Very High | 0.45 / yr | $4M |
| Heat Wave | High | 3.36 / yr | $12M |
| Volcanic Activity | Medium | 0.01 / yr | $675K |
| Riverine Flood | High | 0.39 / yr | $112M |
| Winter Weather | High | 31.89 / yr | $761K |
| Avalanche | High | 0.30 / yr | $2M |
| Lightning | High | 8.63 / yr | $1M |
| Coastal Flood | Medium | 3.18 / yr | $2M |
| Cold Wave | Low | 0.04 / yr | $2M |
| Wildfire | Very Low | 0.00 / yr | $120K |
| Tornado | Low | 0.05 / yr | $1M |
| Hail | Very Low | 0.03 / yr | $66K |
| Drought | Very Low | 4.72 / yr | $44 |
| Strong Wind | Very Low | 0.02 / yr | $74K |
| Tsunami | Very Low | 0.06 / yr | $51K |
| Hurricane | Very Low | 0.00 / yr | $0 |
Disaster History
Snohomish County has received 37 federal disaster declarations since 1964, most recently Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides in April 2026. Most frequent causes: Severe Storm (15), Flood (13), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| April 2026 | Flood | Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides |
| December 2025 | Flood | Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides |
| January 2023 | Severe Storm | Severe Winter Storm, Straight-Line Winds, Flooding, Landslides, and Mudslides |
| September 2022 | Fire | Bolt Creek Fire |
| April 2021 | Severe Storm | Severe Winter Storm, Straight-Line Winds, Flooding, Landslides, and Mudslides |
| April 2020 | Flood | Severe Storms, Flooding, Landslides, and Mudslides |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| March 2019 | Severe Storm | Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, Mudslides, Tornado |
| January 2016 | Severe Storm | Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides |
Showing the 10 most recent of 37 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Snohomish County?
Snohomish County has a composite FEMA National Risk Index score of 97.9 out of 100, placing it in the High category and the 98th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Snohomish County?
The three highest-rated hazards are Landslide (Very High, $25M EAL), Earthquake (High, $247M EAL), Ice Storm (Very High, $4M EAL). These account for most of the county's expected annual losses.
How does Snohomish County compare to other Washington counties?
Snohomish County ranks #3 of 39 Washington counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has Snohomish County had?
FEMA records 37 federal disaster declarations for Snohomish County since 1964, most often 15 for severe storm events and 13 for flood events. The most recent was Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides, declared in April 2026.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Snohomish County's $409M EAL is a statistical average, not a guarantee for any specific year or address.