Rock County
Wisconsin — Natural Disaster Risk Assessment
MediumComposite Risk Score
National percentile: 86th
Rock County faces medium composite natural disaster risk (NRI Risk Index score 86.4, 86th national percentile), driven primarily by hail and tornado exposure. Expected annual loss across all 18 hazard types is $73M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Hail | High | 4.34 / yr | $4M |
| Tornado | High | 0.58 / yr | $13M |
| Cold Wave | High | 5.37 / yr | $13M |
| Riverine Flood | Medium | 2.11 / yr | $38M |
| Strong Wind | High | 5.46 / yr | $2M |
| Lightning | High | 38.50 / yr | $1M |
| Heat Wave | Medium | 3.63 / yr | $2M |
| Winter Weather | Medium | 14.05 / yr | $114K |
| Landslide | Very Low | 0.13 / yr | $3K |
| Earthquake | Very Low | 0.00 / yr | $529K |
| Ice Storm | Low | 0.63 / yr | $147K |
| Drought | Low | 6.60 / yr | $152K |
| Wildfire | Very Low | 0.00 / yr | $14K |
| Hurricane | Very Low | 0.01 / yr | $4K |
| 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 Rock County?
Rock County has a composite FEMA National Risk Index score of 86.4 out of 100, placing it in the Medium category and the 86th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Rock County?
The three highest-rated hazards are Hail (High, $4M EAL), Tornado (High, $13M EAL), Cold Wave (High, $13M EAL). These account for most of the county's expected annual losses.
How does Rock County compare to other Wisconsin counties?
Rock County ranks #7 of 72 Wisconsin 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. Rock County's $73M EAL is a statistical average, not a guarantee for any specific year or address.