riskbycounty
FEMA National Risk Index

St. Clair County Disaster Risk

St. Clair County, Illinois

FEMA Risk Rating

Relatively High

National Percentile

95th

of 3,144 counties

State Rank

#5

of 102 (1 = highest risk)

Flood Risk

94th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Relatively High

Higher than 94% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Very Low

Higher than 15% of US counties

Tornado

Tornado and severe thunderstorm risk

Relatively High

Higher than 95% of US counties

Earthquake

Seismic activity and ground shaking risk

Relatively High

Higher than 98% of US counties

Hurricane

Tropical cyclone and hurricane risk

Very Low

Higher than 35% of US counties

Risk Advisory: St. Clair County

Risk Verdict

St. Clair County carries a relatively high overall disaster risk profile, scoring in the 95th percentile nationally. This places it among the most at-risk counties in the United States. Residents should prioritize comprehensive emergency preparedness, including reviewing insurance coverage and having an evacuation plan.

Hazard Breakdown

Earthquake risk is the dominant hazard for St. Clair County, scoring in the 98th percentile nationally. It is followed by tornado risk at the 95th percentile. Additional hazards include flood (94th), hurricane (35th), wildfire (15th).

Preparedness Context

With earthquake risk as the top concern, St. Clair County residents should secure heavy furniture and appliances, know how to shut off utilities, and keep emergency supplies accessible. Secondary risks such as tornado also warrant attention in household and community preparedness planning. FEMA recommends all households maintain at least 72 hours of food, water, and medication supplies regardless of specific hazard exposure.

Regional Context

St. Clair County is significantly riskier than the average county in Illinois. Its composite risk score is 40.4 points higher than the state average, meaning residents face above-average exposure to natural hazards compared to their neighbors.

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Frequently Asked Questions

What is the natural disaster risk in St. Clair County, IL?
St. Clair County has a FEMA National Risk Index rating of Relatively High, placing it in the 95th percentile nationally out of 3,144 counties. This composite score reflects the county's overall exposure to natural hazards including floods, wildfires, tornadoes, earthquakes, and hurricanes, weighted by expected annual loss and social vulnerability.
What types of natural hazards affect St. Clair County?
St. Clair County is evaluated for five major natural hazard types: earthquake (98th percentile), tornado (95th percentile), flooding (94th percentile), hurricane (35th percentile), wildfire (15th percentile). The highest-risk hazard is earthquake at the 98th percentile nationally. These scores are derived from FEMA's National Risk Index, which analyzes expected annual loss, social vulnerability, and community resilience for each hazard type.
How does St. Clair County risk compare to the Illinois average?
St. Clair County's composite risk percentile is 95th, compared to the Illinois state average of 55th percentile. The state's overall risk rating is Relatively Low. This means St. Clair County faces higher natural disaster risk than the typical county in Illinois.
Is St. Clair County at risk for earthquake?
Yes, St. Clair County's earthquake risk is at the 98th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, St. Clair County is at the 94th percentile.
How is natural disaster risk measured?
FEMA's National Risk Index (NRI) calculates risk scores for 18 natural hazard types across all U.S. counties and census tracts. The composite score combines Expected Annual Loss (estimated dollar losses from each hazard), Social Vulnerability (demographic factors affecting disaster impact), and Community Resilience (ability to recover). Percentile scores rank each county against all 3,144 U.S. counties, and risk ratings range from Very Low to Very High.
Why is St. Clair County higher risk than average?
St. Clair County's composite risk score of 95th percentile is above the Illinois state average of 55th percentile. This elevated risk is driven by earthquake exposure (98th percentile), along with tornado and flooding risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.

Counties with Similar Risk

Kane County

Illinois

-0.3

Relatively High

95th percentile

Lake County

Illinois

+1.1

Relatively High

96th percentile

Madison County

Illinois

-1.5

Relatively Moderate

93th percentile

By Logan Johnson, Founder & Data EditorUpdated Reviewed by Logan Johnson, Founder & Data Editor

Data Source

Risk data sourced from the FEMA National Risk Index (NRI). Risk scores are relative rankings (0–100) across all US counties — not absolute risk measures. Higher scores indicate higher relative risk compared to other counties.

Disclaimer: This data is informational only. It is not financial, insurance, or legal advice. Always consult a qualified professional before making insurance or real estate decisions.

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