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 Overview
About Natural Disaster Risk in St. Clair County, Illinois
St. Clair faces highest state risk
St. Clair County scores 94.91 on the composite risk scale, earning a Relatively High rating and exceeding Illinois's state average of 54.46 by nearly 75%. This southwestern county faces the most serious natural disaster exposure in Illinois across multiple compounded hazard types.
Riskiest county in Illinois
St. Clair ranks as the highest-risk county in Illinois by composite score at 94.91, surpassing 95% of the state's other counties. The county faces exceptional exposure to tornadoes (95.45), floods (94.50), and earthquakes (98.03)—a dangerous convergence of multiple hazards.
Extreme risk in regional context
St. Clair's 94.91 score exceeds all neighboring counties, with only Sangamon County (91.70) approaching similar risk levels elsewhere in the state. The county sits at the intersection of the Mississippi River floodplain, active earthquake zones, and tornado alley, creating compounding hazard exposure.
Earthquakes, tornadoes, and floods
St. Clair residents face exceptional earthquake risk at 98.03, tornado exposure at 95.45, and severe flood danger at 94.50—all among the state's highest. The combination of riverine flooding potential, seismic activity, and severe convective weather demands comprehensive preparedness across all three major hazard types.
Maximum protection is essential
St. Clair County homeowners must maintain comprehensive flood insurance through the NFIP, earthquake insurance, and robust tornado coverage as non-negotiable essentials. Invest in structural reinforcement including tornado-safe rooms and seismic tie-downs, maintain substantial emergency supplies, and review all insurance policies annually with a local agent familiar with compound-hazard risk.
Source: FEMA National Risk Index · Narrative reviewed by Evan Brooks, Data Editor
Preparedness Guide
What to Prepare for in St. Clair County
Top Hazards by Exposure
Source: FEMA National Risk Index v1.19.0 · Percentiles are national (3,144 counties)
Risk Advisory: St. Clair County
Risk Verdict
Natural hazard exposure in St. Clair County is notably high, placing it at the 95th percentile among all U.S. counties. St. Clair County's elevated composite score reflects cumulative multi-hazard exposure; households should prepare for the county's two or three primary hazard types.
Hazard Breakdown
Earthquake risk is St. Clair County's dominant natural hazard, ranked at the 98th percentile nationally under FEMA's National Risk Index. Tornado ranks second at the 95th percentile nationally. Additional tracked hazards include flood (94th percentile), hurricane (35th percentile), wildfire (15th percentile).
Preparedness Context
At the 98th percentile nationally for earthquake risk, St. Clair County is in a zone where a post-earthquake communications plan matters almost as much as pre-earthquake structural preparation — phone networks are typically congested for hours after a significant event. Alongside earthquake exposure, St. Clair County's tornado risk at the 95th percentile nationally reinforces the value of maintaining a household emergency supply cache usable for multiple hazard scenarios. For St. Clair County households, the three highest-impact earthquake preparedness actions are: (1) anchor heavy furniture and water heaters, (2) store three days of water at one gallon per person per day, and (3) identify a family reunification plan for the post-quake communication blackout period.
Regional Context
A composite score 40.4 points above the Illinois state average puts St. Clair County in a higher-risk category than most counties in the state.
Is your household prepared for St. Clair County's hazards?
Review FEMA's county-specific preparedness checklists and emergency planning guides.
Frequently Asked Questions
What is the natural disaster risk in St. Clair County, IL?
What types of natural hazards affect St. Clair County?
How does St. Clair County risk compare to the Illinois average?
Is St. Clair County at risk for earthquake?
How is natural disaster risk measured?
Why is St. Clair County higher risk than average?
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.