Mason County
Washington — Natural Disaster Risk Assessment
MediumComposite Risk Score
National percentile: 85th
Mason County faces medium composite natural disaster risk (NRI Risk Index score 85.3, 85th national percentile), driven primarily by landslide and earthquake exposure. Expected annual loss across all 18 hazard types is $44M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Landslide | High | 10.89 / yr | $500K |
| Earthquake | Medium | 0.03 / yr | $26M |
| Riverine Flood | Medium | 0.18 / yr | $15M |
| Coastal Flood | Medium | 3.15 / yr | $1M |
| Heat Wave | Low | 2.67 / yr | $653K |
| Volcanic Activity | Very Low | 0.00 / yr | $8 |
| Winter Weather | Low | 11.83 / yr | $47K |
| Wildfire | Very Low | 0.00 / yr | $26K |
| Tsunami | Very Low | 0.06 / yr | $433K |
| Avalanche | Very Low | 0.01 / yr | $225 |
| Ice Storm | Very Low | 0.31 / yr | $19K |
| Lightning | Very Low | 5.15 / yr | $54K |
| Tornado | Very Low | 0.04 / yr | $94K |
| Drought | Very Low | 1.27 / yr | $5 |
| Strong Wind | Very Low | 0.01 / yr | $33K |
| Hail | Very Low | 0.01 / yr | $4K |
| Cold Wave | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Mason County?
Mason County has a composite FEMA National Risk Index score of 85.3 out of 100, placing it in the Medium category and the 85th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Mason County?
The three highest-rated hazards are Landslide (High, $500K EAL), Earthquake (Medium, $26M EAL), Riverine Flood (Medium, $15M EAL). These account for most of the county's expected annual losses.
How does Mason County compare to other Washington counties?
Mason County ranks #20 of 39 Washington counties for overall natural disaster risk, with a medium rating.
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. Mason County's $44M EAL is a statistical average, not a guarantee for any specific year or address.