Williamson County, Texas Natural Disaster Risk
FEMA National Risk Index assessment · TX
MediumComposite Risk Score
National percentile: 90th
Williamson County faces medium composite natural disaster risk (NRI Risk Index score 90.1, 90th national percentile), driven primarily by hail and winter weather exposure. Expected annual loss across all 18 hazard types is $137M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Williamson County is medium, with a National Risk Index score of 90.1 out of 100 — placing it in the 90th national percentile and near the national midpoint for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in hail (ice stones from severe thunderstorms that damage property and crops) at High risk — $14M in expected annual loss and about 3.95 events per year; winter weather (heavy snow, blizzards, and hazardous winter conditions) at Very High risk — $1M in expected annual loss and about 3.74 events per year; and cold wave (prolonged spells of dangerously low temperatures) at High risk — $21M in expected annual loss and about 0.63 events per year. Across all hazards, FEMA estimates $137M in expected annual loss for a population of 608K.
Beyond physical exposure, Williamson County has a very low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
History supports the rating: Williamson County has received 26 federal disaster declarations since 1974, including 8 for fire events and 4 for severe storm events. The most recent was Severe Storms, Straight-Line Winds, and Flooding (flood), declared in July 2025.
Among 254 Texas counties, Williamson County ranks #24 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Hail | High | 3.95 / yr | $14M |
| Winter Weather | Very High | 3.74 / yr | $1M |
| Cold Wave | High | 0.63 / yr | $21M |
| Tornado | High | 0.62 / yr | $17M |
| Riverine Flood | Medium | 3.64 / yr | $71M |
| Heat Wave | Medium | 10.00 / yr | $5M |
| Lightning | High | 49.36 / yr | $2M |
| Wildfire | Low | 0.00 / yr | $2M |
| Ice Storm | Medium | 0.65 / yr | $403K |
| Drought | Medium | 59.30 / yr | $964K |
| Hurricane | Low | 0.04 / yr | $860K |
| Strong Wind | Medium | 1.72 / yr | $1M |
| Earthquake | Very Low | 0.00 / yr | $197K |
| Landslide | Very Low | 0.13 / yr | $278 |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Williamson County has received 26 federal disaster declarations since 1974, most recently Severe Storms, Straight-Line Winds, and Flooding in July 2025. Most frequent causes: Fire (8), Severe Storm (4), Hurricane (4).
| Declared | Type | Disaster |
|---|---|---|
| July 2025 | Flood | Severe Storms, Straight-Line Winds, and Flooding |
| April 2023 | Winter Storm | Severe Winter Storm |
| February 2021 | Severe Ice Storm | Severe Winter Storms |
| February 2021 | Severe Ice Storm | Severe Winter Storm |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| May 2015 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds and Flooding |
| September 2011 | Fire | Wildfires |
| September 2011 | Fire | Moonglow Fire |
| August 2011 | Fire | Horseshoe Fire |
Showing the 10 most recent of 26 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Williamson County?
Williamson County has a composite FEMA National Risk Index score of 90.1 out of 100, placing it in the Medium category and the 90th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Williamson County?
The three highest-rated hazards are Hail (High, $14M EAL), Winter Weather (Very High, $1M EAL), Cold Wave (High, $21M EAL). These account for most of the county's expected annual losses.
How does Williamson County compare to other Texas counties?
Williamson County ranks #24 of 254 Texas counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Williamson County had?
FEMA records 26 federal disaster declarations for Williamson County since 1974, most often 8 for fire events and 4 for severe storm events. The most recent was Severe Storms, Straight-Line Winds, and Flooding, declared in July 2025.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Williamson County's $137M EAL is a statistical average, not a guarantee for any specific year or address.