Washington County, Oregon Natural Disaster Risk
FEMA National Risk Index assessment · OR
HighComposite Risk Score
National percentile: 96th
Washington County faces high composite natural disaster risk (NRI Risk Index score 96.0, 96th national percentile), driven primarily by earthquake and heat wave exposure. Expected annual loss across all 18 hazard types is $270M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Washington County carries a high composite natural disaster risk, with a National Risk Index score of 96.0 out of 100 — placing it in the 96th 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.
The county's risk is driven primarily by earthquake (ground shaking from sudden movement along geologic faults) at High risk — $163M in expected annual loss and about 0.01 events per year; heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at High risk — $11M in expected annual loss and about 6.25 events per year; and riverine flood (rivers and streams overflowing their banks after heavy rain or snowmelt) at High risk — $81M in expected annual loss and about 0.75 events per year. Across all hazards, FEMA estimates $270M in expected annual loss for a population of 600K.
Beyond physical exposure, Washington 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.
History supports the rating: Washington County has received 17 federal disaster declarations since 1964, including 5 for fire events and 4 for severe storm events. The most recent was Lee Falls Fire (fire), declared in August 2024.
Among 36 Oregon counties, Washington County ranks #3 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Earthquake | High | 0.01 / yr | $163M |
| Heat Wave | High | 6.25 / yr | $11M |
| Riverine Flood | High | 0.75 / yr | $81M |
| Ice Storm | High | 1.22 / yr | $1M |
| Cold Wave | High | 0.23 / yr | $9M |
| Volcanic Activity | Low | 0.01 / yr | $16K |
| Landslide | Low | 3.91 / yr | $43K |
| Lightning | Medium | 5.88 / yr | $1M |
| Strong Wind | Medium | 0.05 / yr | $2M |
| Winter Weather | Medium | 10.65 / yr | $216K |
| Tornado | Low | 0.07 / yr | $2M |
| Wildfire | Very Low | 0.00 / yr | $65K |
| Hail | Very Low | 0.05 / yr | $151K |
| Drought | Very Low | 0.19 / yr | $0 |
| Avalanche | Very Low | 0.01 / yr | $11 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
Disaster History
Washington County has received 17 federal disaster declarations since 1964, most recently Lee Falls Fire in August 2024. Most frequent causes: Fire (5), Severe Storm (4), Flood (4).
| Declared | Type | Disaster |
|---|---|---|
| August 2024 | Fire | Lee Falls Fire |
| September 2020 | Fire | Wildfires and Straight-Line Winds |
| September 2020 | Fire | Wildfires |
| September 2020 | Fire | Chehalem Mountain Bald Peak Fire |
| September 2020 | Fire | Powerline Fire |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| February 2016 | Severe Storm | Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides |
| March 2009 | Severe Storm | Severe Winter Storm, Record and Near Record Snow |
| December 2007 | Severe Storm | Severe Storms, Flooding, Landslides, and Mudslides |
Showing the 10 most recent of 17 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Washington County?
Washington County has a composite FEMA National Risk Index score of 96.0 out of 100, placing it in the High category and the 96th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Washington County?
The three highest-rated hazards are Earthquake (High, $163M EAL), Heat Wave (High, $11M EAL), Riverine Flood (High, $81M EAL). These account for most of the county's expected annual losses.
How does Washington County compare to other Oregon counties?
Washington County ranks #3 of 36 Oregon counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has Washington County had?
FEMA records 17 federal disaster declarations for Washington County since 1964, most often 5 for fire events and 4 for severe storm events. The most recent was Lee Falls Fire, declared in August 2024.
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. Washington County's $270M EAL is a statistical average, not a guarantee for any specific year or address.