King County, Washington Natural Disaster Risk
FEMA National Risk Index assessment · WA
Very HighComposite Risk Score
National percentile: 100th
King County faces very high composite natural disaster risk (NRI Risk Index score 99.7, 100th national percentile), driven primarily by earthquake and riverine flood exposure. Expected annual loss across all 18 hazard types is $1.68B.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in King County is very high, with a National Risk Index score of 99.7 out of 100 — placing it in the 100th national percentile and among the most at-risk counties in the United States. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
The county's risk is driven primarily by earthquake (ground shaking from sudden movement along geologic faults) at Very High risk — $1.21B in expected annual loss and about 0.05 events per year; riverine flood (rivers and streams overflowing their banks after heavy rain or snowmelt) at Very High risk — $417M in expected annual loss and about 0.29 events per year; and avalanche (fast-moving snow and debris sliding down steep mountain slopes) at Very High risk — $11M in expected annual loss and about 1.07 events per year. Across all hazards, FEMA estimates $1.68B in expected annual loss for a population of 2.27M.
Beyond physical exposure, King County has a very low social vulnerability rating (how susceptible the population is to harm) and a very 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 federal record bears this out: King County has received 35 federal disaster declarations since 1964, including 17 for flood events and 11 for severe storm events. The most recent was Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides (flood), declared in April 2026.
Among 39 Washington counties, King County ranks #1 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Earthquake | Very High | 0.05 / yr | $1.21B |
| Riverine Flood | Very High | 0.29 / yr | $417M |
| Avalanche | Very High | 1.07 / yr | $11M |
| Landslide | High | 4.28 / yr | $2M |
| Heat Wave | High | 3.81 / yr | $19M |
| Volcanic Activity | High | 0.01 / yr | $2M |
| Winter Weather | High | 26.87 / yr | $815K |
| Ice Storm | High | 0.77 / yr | $1M |
| Wildfire | Low | 0.00 / yr | $487K |
| Lightning | Medium | 9.87 / yr | $750K |
| Tornado | Medium | 0.07 / yr | $4M |
| Coastal Flood | Medium | 3.18 / yr | $1M |
| Tsunami | Low | 0.06 / yr | $6M |
| Cold Wave | Low | 0.05 / yr | $449K |
| Drought | Very Low | 3.99 / yr | $240 |
| Strong Wind | Very Low | 0.01 / yr | $39K |
| Hail | Very Low | 0.03 / yr | $8K |
| Hurricane | Very Low | 0.00 / yr | $0 |
Disaster History
King County has received 35 federal disaster declarations since 1964, most recently Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides in April 2026. Most frequent causes: Flood (17), Severe Storm (11), 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 |
| April 2024 | Severe Storm | Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides |
| September 2022 | Fire | Bolt Creek Fire |
| April 2020 | Flood | Severe Storms, Flooding, Landslides, and Mudslides |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| April 2017 | Flood | Severe Winter Storms, Flooding, Landslides, Mudslides |
| March 2012 | Severe Storm | Severe Winter Storm, Flooding, Landslides, and Mudslides |
| March 2011 | Severe Storm | Severe Winter Storm, Flooding, Landslides, and Mudslides |
Showing the 10 most recent of 35 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for King County?
King County has a composite FEMA National Risk Index score of 99.7 out of 100, placing it in the Very High category and the 100th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in King County?
The three highest-rated hazards are Earthquake (Very High, $1.21B EAL), Riverine Flood (Very High, $417M EAL), Avalanche (Very High, $11M EAL). These account for most of the county's expected annual losses.
How does King County compare to other Washington counties?
King County ranks #1 of 39 Washington counties for overall natural disaster risk, with a very high rating.
How many federally declared disasters has King County had?
FEMA records 35 federal disaster declarations for King County since 1964, most often 17 for flood events and 11 for severe storm 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. King County's $1.68B EAL is a statistical average, not a guarantee for any specific year or address.