Washtenaw County
Michigan — Natural Disaster Risk Assessment
MediumComposite Risk Score
National percentile: 89th
Washtenaw County faces medium composite natural disaster risk (NRI Risk Index score 89.3, 89th national percentile), driven primarily by strong wind and tornado exposure. Expected annual loss across all 18 hazard types is $93M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Strong Wind | High | 5.70 / yr | $6M |
| Tornado | High | 0.35 / yr | $21M |
| Cold Wave | High | 2.79 / yr | $11M |
| Ice Storm | High | 1.78 / yr | $1M |
| Riverine Flood | Medium | 1.18 / yr | $47M |
| Lightning | High | 36.85 / yr | $1M |
| Heat Wave | Medium | 3.68 / yr | $3M |
| Hail | Medium | 3.14 / yr | $1M |
| Earthquake | Low | 0.00 / yr | $1M |
| Winter Weather | Medium | 10.47 / yr | $179K |
| Landslide | Low | 0.18 / yr | $7K |
| Hurricane | Very Low | 0.01 / yr | $73K |
| Wildfire | Very Low | 0.00 / yr | $38K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Drought | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Washtenaw County?
Washtenaw County has a composite FEMA National Risk Index score of 89.3 out of 100, placing it in the Medium category and the 89th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Washtenaw County?
The three highest-rated hazards are Strong Wind (High, $6M EAL), Tornado (High, $21M EAL), Cold Wave (High, $11M EAL). These account for most of the county's expected annual losses.
How does Washtenaw County compare to other Michigan counties?
Washtenaw County ranks #6 of 83 Michigan 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. Washtenaw County's $93M EAL is a statistical average, not a guarantee for any specific year or address.