riskbycounty
FEMA National Risk Index

Williamson County Disaster Risk

Williamson County, Illinois

FEMA Risk Rating

Relatively Moderate

National Percentile

86th

of 3,144 counties

State Rank

#17

of 102 (1 = highest risk)

Flood Risk

70th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Relatively Low

Higher than 70% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Very Low

Higher than 14% of US counties

Tornado

Tornado and severe thunderstorm risk

Relatively Low

Higher than 80% of US counties

Earthquake

Seismic activity and ground shaking risk

Relatively High

Higher than 96% of US counties

Hurricane

Tropical cyclone and hurricane risk

Relatively Low

Higher than 45% of US counties

Risk Advisory: Williamson County

Risk Verdict

Williamson County has a relatively moderate overall disaster risk profile, scoring in the 86th percentile nationally. While not in the highest tier, this county faces meaningful hazard exposure. Residents are encouraged to understand their specific risks and maintain emergency supplies.

Hazard Breakdown

Earthquake risk is the dominant hazard for Williamson County, scoring in the 96th percentile nationally. It is followed by tornado risk at the 80th percentile. Additional hazards include flood (70th), hurricane (45th), wildfire (14th).

Preparedness Context

With earthquake risk as the top concern, Williamson 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

Williamson County is significantly riskier than the average county in Illinois. Its composite risk score is 31.3 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 Williamson County, IL?
Williamson County has a FEMA National Risk Index rating of Relatively Moderate, placing it in the 86th 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 Williamson County?
Williamson County is evaluated for five major natural hazard types: earthquake (96th percentile), tornado (80th percentile), flooding (70th percentile), hurricane (45th percentile), wildfire (14th percentile). The highest-risk hazard is earthquake at the 96th 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 Williamson County risk compare to the Illinois average?
Williamson County's composite risk percentile is 86th, compared to the Illinois state average of 55th percentile. The state's overall risk rating is Relatively Low. This means Williamson County faces higher natural disaster risk than the typical county in Illinois.
Is Williamson County at risk for earthquake?
Yes, Williamson County's earthquake risk is at the 96th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Williamson County is at the 70th 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 Williamson County higher risk than average?
Williamson County's composite risk score of 86th percentile is above the Illinois state average of 55th percentile. This elevated risk is driven by earthquake exposure (96th 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

LaSalle County

Illinois

+0.3

Relatively Moderate

86th percentile

McLean County

Illinois

+1.1

Relatively Moderate

87th percentile

Jackson County

Illinois

+1.3

Relatively Moderate

87th 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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