St. Clair County
Illinois — Natural Disaster Risk Assessment
HighComposite Risk Score
National percentile: 95th
St. Clair County faces high composite natural disaster risk (NRI Risk Index score 94.9, 95th national percentile), driven primarily by heat wave and earthquake exposure. Expected annual loss across all 18 hazard types is $175M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Heat Wave | High | 14.79 / yr | $15M |
| Earthquake | Medium | 0.01 / yr | $51M |
| Hail | High | 5.20 / yr | $5M |
| Cold Wave | High | 1.42 / yr | $15M |
| Tornado | High | 0.58 / yr | $13M |
| Riverine Flood | High | 1.79 / yr | $72M |
| Lightning | High | 51.93 / yr | $2M |
| Ice Storm | High | 1.39 / yr | $1M |
| Winter Weather | High | 9.00 / yr | $333K |
| Landslide | Low | 0.46 / yr | $28K |
| Drought | Low | 1.66 / yr | $314K |
| Strong Wind | Medium | 6.15 / yr | $627K |
| Hurricane | Very Low | 0.01 / yr | $21K |
| Wildfire | Very Low | 0.00 / yr | $5K |
| 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 St. Clair County?
St. Clair County has a composite FEMA National Risk Index score of 94.9 out of 100, placing it in the High category and the 95th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in St. Clair County?
The three highest-rated hazards are Heat Wave (High, $15M EAL), Earthquake (Medium, $51M EAL), Hail (High, $5M EAL). These account for most of the county's expected annual losses.
How does St. Clair County compare to other Illinois counties?
St. Clair County ranks #5 of 102 Illinois counties for overall natural disaster risk, with a high 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. St. Clair County's $175M EAL is a statistical average, not a guarantee for any specific year or address.