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

Williamson County Disaster Risk

Williamson County, Tennessee

FEMA Risk Rating

Relatively Moderate

National Percentile

85th

of 3,144 counties

State Rank

#11

of 95 (1 = highest risk)

Flood Risk

88th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Moderate

Higher than 88% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Very Low

Higher than 40% of US counties

Tornado

Tornado and severe thunderstorm risk

Moderate

Higher than 89% of US counties

Earthquake

Seismic activity and ground shaking risk

Moderate

Higher than 89% of US counties

Hurricane

Tropical cyclone and hurricane risk

Very Low

Higher than 41% of US counties

Risk Overview

About Natural Disaster Risk in Williamson County, Tennessee

Williamson County's notable risk elevation

Williamson County scores 85.15 on the composite risk scale, placing it significantly above Tennessee's state average of 52.45 in the 'Relatively Moderate' risk category. The county faces elevated exposure to multiple hazards, making it one of Tennessee's highest-risk communities.

Among Tennessee's highest-risk counties

Williamson County ranks in the upper tier of Tennessee's 95 counties by composite risk, with its 85.15 score among the state's most concerning. The county's multi-hazard vulnerability across floods, tornadoes, and earthquakes places it well above typical state conditions.

Williamson's exceptional risk profile

Williamson County (85.15) faces substantially higher risk than all nearby counties, including Warren County (63.45), Washington County (61.16), and Wilson County (79.99). The county's 'Relatively Moderate' rating is the highest among its peers, reflecting distinctive hazard exposure in the Nashville metropolitan area.

Williamson's three critical hazards

Tornadoes (88.87), earthquakes (89.41), and floods (88.23) dominate Williamson County's disaster risks, with all three scoring near the national high end. These three hazards collectively represent exceptional vulnerability, requiring comprehensive preparedness planning across multiple threat types.

Comprehensive coverage is critical

Williamson County residents must secure flood insurance, earthquake coverage, and maintain robust homeowners policies, given the county's exceptional multi-hazard exposure. The county's 85.15 composite score demands the highest level of disaster preparedness, including documented emergency plans and reinforced shelter areas.

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
    EarthquakePrepare
    89th percentile
  2. #2
    TornadoPrepare
    89th percentile
  3. #3
    FloodPrepare
    88th percentile

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

Risk Advisory: Williamson County

Risk Verdict

Williamson County faces a moderate natural disaster risk profile, ranking at the 85th percentile nationally under FEMA's composite risk model. This risk level calls for more than general awareness: insurance coverage review, a family communication plan, and a prepared go-bag are practical priorities.

Hazard Breakdown

Earthquake risk is Williamson County's dominant natural hazard, ranked at the 89th percentile nationally under FEMA's National Risk Index. Tornado ranks second at the 89th percentile nationally. Additional tracked hazards include flood (88th percentile), hurricane (41th percentile), wildfire (40th percentile).

Preparedness Context

Earthquake risk is Williamson County's leading natural hazard, ranked at the 89th percentile nationally. Securing tall furniture, water heaters, and bookcases to walls with anti-tip hardware is among the simplest and most effective life-safety measures households can take. Alongside earthquake exposure, Williamson County's tornado risk at the 89th percentile nationally reinforces the value of maintaining a household emergency supply cache usable for multiple hazard scenarios. Williamson County residents should locate the main gas shutoff valve and keep an appropriate wrench nearby — gas leaks cause a significant share of earthquake-related injuries and fires, and the shutoff step is safe to take immediately after shaking stops.

Regional Context

Williamson County's composite risk score sits 32.7 points above the Tennessee county average, placing it among the more hazard-exposed counties in the state.

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, TN?
Williamson County has a FEMA National Risk Index rating of Relatively Moderate, placing it in the 85th 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 (89th percentile), tornado (89th percentile), flooding (88th percentile), hurricane (41th percentile), wildfire (40th percentile). The highest-risk hazard is earthquake at the 89th 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 Tennessee average?
Williamson County's composite risk percentile is 85th, compared to the Tennessee state average of 53th percentile. The state's overall risk rating is Relatively Low. This means Williamson County faces higher natural disaster risk than the typical county in Tennessee.
Is Williamson County at risk for earthquake?
Yes, Williamson County's earthquake risk is at the 89th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Williamson County is at the 88th 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 85th percentile is above the Tennessee state average of 53th percentile. This elevated risk is driven by earthquake exposure (89th 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.
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.