Williamson County
Tennessee — Natural Disaster Risk Assessment
MediumComposite Risk Score
National percentile: 85th
Williamson County faces medium composite natural disaster risk (NRI Risk Index score 85.1, 85th national percentile), driven primarily by cold wave and earthquake exposure. Expected annual loss across all 18 hazard types is $98M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Cold Wave | High | 1.16 / yr | $13M |
| Earthquake | Low | 0.00 / yr | $8M |
| Strong Wind | High | 6.11 / yr | $3M |
| Tornado | Medium | 0.51 / yr | $12M |
| Riverine Flood | Medium | 2.18 / yr | $57M |
| Winter Weather | Medium | 5.16 / yr | $469K |
| Ice Storm | High | 0.62 / yr | $1M |
| Heat Wave | Low | 4.95 / yr | $2M |
| Landslide | Very Low | 0.86 / yr | $3K |
| Lightning | Low | 60.55 / yr | $468K |
| Hail | Low | 3.50 / yr | $332K |
| Hurricane | Very Low | 0.02 / yr | $55K |
| Wildfire | Very Low | 0.00 / yr | $45K |
| Drought | Low | 9.57 / yr | $77K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | 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 Williamson County?
Williamson County has a composite FEMA National Risk Index score of 85.1 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 Williamson County?
The three highest-rated hazards are Cold Wave (High, $13M EAL), Earthquake (Low, $8M EAL), Strong Wind (High, $3M EAL). These account for most of the county's expected annual losses.
How does Williamson County compare to other Tennessee counties?
Williamson County ranks #11 of 95 Tennessee 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. Williamson County's $98M EAL is a statistical average, not a guarantee for any specific year or address.