riskbycounty
FEMA NRI 1.19.0Updated Nov 2023 · Coverage 2014–2023Methodology

Williamson County Disaster Risk

Williamson County, Texas

FEMA Risk Rating

Relatively Moderate

National Percentile

90th

of 3,144 counties

State Rank

#24

of 254 (1 = highest risk)

Flood Risk

91th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Moderate

Higher than 91% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Moderate

Higher than 88% of US counties

Tornado

Tornado and severe thunderstorm risk

Moderate

Higher than 94% of US counties

Earthquake

Seismic activity and ground shaking risk

Very Low

Higher than 36% of US counties

Hurricane

Tropical cyclone and hurricane risk

Relatively Low

Higher than 69% of US counties

Risk Overview

About Natural Disaster Risk in Williamson County, Texas

Williamson faces among Texas's highest risks

Williamson County's composite risk score of 90.11 ranks as one of the highest in the nation, classified "Relatively Moderate" but well above the national average. This score reflects a county where residents contend with multiple severe weather hazards simultaneously.

One of Texas's riskiest counties

Williamson's score of 90.11 dramatically exceeds the Texas state average of 49.00, placing it among the highest-risk counties in the state. Rapid growth and development in flood-prone areas compound these natural hazard exposures.

Significantly riskier than central Texas peers

Williamson County (90.11) faces substantially higher risk than Wilson County (75.54) to the south and the state average overall. Its Austin-area location concentrates flood, tornado, and wildfire exposure in an urbanizing landscape.

Tornadoes, floods, and wildfires converge

Williamson's tornado risk of 93.86 is among the state's highest, while flood risk of 91.32 and wildfire risk of 87.82 round out a severe hazard profile. The county sits in a corridor where multiple weather systems and fire-prone terrain align.

Comprehensive coverage is absolutely essential

Williamson County homeowners must secure full-coverage homeowners insurance with wind and hail protection, plus a separate flood insurance policy for flood-prone properties. For properties in wildfire-adjacent areas, additional wildfire coverage or mitigation improvements are prudent investments.

Source: FEMA National Risk Index · Narrative reviewed by Evan Brooks, Data Editor

Preparedness Guide

What to Prepare for in Williamson County

Top Hazards by Exposure

  1. #1
    TornadoPrepare
    94th percentile
  2. #2
    FloodPrepare
    91th percentile
  3. #3
    WildfirePrepare
    88th percentile

Source: FEMA National Risk Index v1.19.0 · Percentiles are national (3,144 counties)

Risk Advisory: Williamson County

Risk Verdict

Williamson County's overall risk score at the 90th percentile nationally signals meaningful exposure to multiple natural hazard types. Comprehensive household preparedness — including reviewing insurance, maintaining emergency supplies, and knowing evacuation routes — is strongly recommended.

Hazard Breakdown

Tornado risk is Williamson County's dominant natural hazard, ranked at the 94th percentile nationally under FEMA's National Risk Index. Flood ranks second at the 91th percentile nationally. Additional tracked hazards include wildfire (88th percentile), hurricane (69th percentile), earthquake (36th percentile).

Preparedness Context

Williamson County ranks at the 94th percentile nationally for tornado exposure. Unlike many slow-onset hazards, tornadoes in Williamson County can reach full intensity in minutes; a pre-practiced household shelter plan matters far more than stockpiled supplies. Flood is the second hazard driver for Williamson County at the 91th percentile nationally, meaning households should maintain awareness of both severe-weather and flood-specific warning systems. Williamson County county emergency management typically publishes annual severe-weather preparedness guides tailored to local tornado patterns; households benefit from reviewing these before storm season begins each spring.

Regional Context

Compared to other Texas counties, Williamson County runs 41.1 composite risk points higher than the state mean — reflecting above-average hazard concentration in this area.

Is your household prepared for Williamson County's hazards?

Review FEMA's county-specific preparedness checklists and emergency planning guides.

FEMA Ready Guide →

Frequently Asked Questions

What is the natural disaster risk in Williamson County, TX?
Williamson County has a FEMA National Risk Index rating of Relatively Moderate, placing it in the 90th 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: tornado (94th percentile), flooding (91th percentile), wildfire (88th percentile), hurricane (69th percentile), earthquake (36th percentile). The highest-risk hazard is tornado at the 94th 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 Texas average?
Williamson County's composite risk percentile is 90th, compared to the Texas state average of 49th percentile. The state's overall risk rating is Relatively Low. This means Williamson County faces higher natural disaster risk than the typical county in Texas.
Is Williamson County at risk for tornado?
Yes, Williamson County's tornado risk is at the 94th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Williamson County is at the 91th 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 90th percentile is above the Texas state average of 49th percentile. This elevated risk is driven by tornado exposure (94th percentile), along with flooding and wildfire and hurricane risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.
By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, 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.