Williamson County, TN
FEMA National Risk Index scores, disaster declarations & hazard data
Williamson County has experienced 16 federally declared disasters since 1974, most recently Severe Winter Storm in 2026. Its overall natural hazard risk is rated Relatively Moderate — near the middle compared to other US counties.
Williamson County's highest-rated hazards are cold wave, earthquake, and strong wind, with its top risk rated "Relatively High" by FEMA's National Risk Index. Recorded storm events have increased 111% over the past five years compared to the prior five-year period. Community vulnerability is relatively low (2nd percentile nationally), indicating stronger recovery capacity than most US counties.
Past disasters & FEMA designations
A federal disaster declaration officially designates a county for FEMA disaster assistance. Williamson County has been designated in 16 declarations since 1974, covering 6 disaster types including severe storm (8), winter storm (2), tornado (2).
| Year | Type | Event name |
|---|---|---|
| 2026 | Winter Storm | Severe Winter Storm |
| 2026 | Winter Storm | Severe Winter Storm |
| 2025 | Severe Storm | Severe Storms, Straight-Line Winds, Tornadoes, And Flooding |
| 2021 | Tornado | Severe Storms, Tornadoes, And Flooding |
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2010 | Severe Storm | Severe Storms, Flooding, Straight-Line Winds, And Tornadoes |
| 2008 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, And Flooding |
| 2005 | Hurricane | Hurricane Katrina Evacuation |
| 2003 | Severe Storm | Severe Storms, Tornadoes, And Flooding |
Showing the 10 most recent of 16 total declarations since 1974.
Source: FEMA OpenFEMA Disaster Declarations Summaries. A single disaster can produce more than one record per county. Data current through September 2026.
Risk by hazard type
| Hazard | Risk rating | Risk score | Recorded events | Deaths | Prop. damage |
|---|---|---|---|---|---|
| Wildfire | Very Low | 39.8 | 0 | 0 | — |
| Inland Flooding | Relatively Moderate | 88.2 | 48 | 0 | $1.9M |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Relatively Low | 89.4 | — | — | — |
| Heat Wave | Relatively Low | 72.5 | 3 | 0 | — |
| Tornado | Relatively Moderate | 88.9 | 6 | 0 | $7.4M |
| Hurricane | Very Low | 41 | 0 | 0 | — |
| Hail | Relatively Low | 41.9 | 99 | 0 | $100K |
| Strong Wind | Relatively High | 89.1 | 0 | 0 | — |
| Winter Weather | Relatively Moderate | 84.7 | 0 | 0 | — |
| Ice Storm | Relatively High | 84.4 | — | — | — |
| Cold Wave | Relatively High | 90.7 | — | — | — |
| Lightning | Relatively Low | 53.7 | 9 | 0 | $603K |
| Drought | Relatively Low | 35.8 | 0 | 0 | — |
| Landslide | Very Low | 54.2 | 0 | 0 | — |
| Avalanche | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic Activity | Not Applicable | — | — | — | — |
Scores are 0–100 percentiles relative to all US counties — higher means more exposed, not that a disaster is likely this year. Event counts: NOAA Storm Events 2016–2026; earthquake counts from USGS ComCat (M3.0+, 1996–2026). See the methodology page for details.
Community vulnerability
Williamson County ranks in the 2nd percentile (Very low) for community vulnerability — a measure of how hard disaster impacts tend to hit residents. Higher vulnerability means more displacement, worse health outcomes, and slower recovery after a disaster.
| SVI theme | Percentile | Vulnerability level |
|---|---|---|
| Overall | 2nd | Very low |
| Socioeconomic status | 0th | Very low |
| Household characteristics | 14th | Very low |
| Racial & ethnic minority status | 48th | Low |
| Housing type & transportation | 4th | Very low |
Source: CDC/ATSDR Social Vulnerability Index 2022. Percentiles compare counties nationally — higher means more vulnerable relative to other counties. See CDC SVI for full methodology.
Future risk outlook
| Wildfire metric | National percentile | Level |
|---|---|---|
| Burn probability | 25th | Relatively Low |
| Risk to homes | 23rd | Relatively Low |
| Buildings in direct exposure zone | 58.4% | — |
NOAA tracked 165 weather events in this county over 2016–2025: 53 in 2016–20 vs 112 in 2021–25 (+111% — frequency increasing).
Wildfire: USDA Forest Service Wildfire Risk to Communities (RDS-2020-0016-2) — modeled values, not annual forecasts. See wildfirerisk.org. Inland flood and heat projections pending data availability; coastal sea-level projections are available for select coastal counties below — see the data page.
Nearby counties
Frequently asked questions
What natural hazards pose the greatest risk in Williamson County?
According to the FEMA National Risk Index, the highest-risk hazards in Williamson County, Tennessee are cold wave, earthquake, and strong wind. The county's overall natural hazard risk is rated Relatively Moderate — near the middle compared to other US counties.
Has Williamson County received federal disaster declarations?
Yes. Williamson County has received 16 federal disaster declarations since 1974, including declarations in 2026. The most common disaster type on record is severe storm (8 declarations).
Has Williamson County had any FEMA disaster declarations in 2024, 2025, or 2026?
Yes. Recent federal disaster declarations for Williamson County include Severe Winter Storm (2026), Severe Winter Storm (2026), Severe Storms, Straight-Line Winds, Tornadoes, And Flooding (2025). See the declarations table above for the full history since 1974.
How does Williamson County's natural hazard risk compare to nearby counties?
Among neighboring counties, Davidson County, TN has the highest overall natural hazard risk (Relatively High) and Marshall County, TN has the lowest (Relatively Low). Williamson County is rated Relatively Moderate overall.
How is Williamson County's composite disaster risk index calculated?
Williamson County's composite disaster risk index — officially FEMA's National Risk Index (NRI) — scores every US county on a 0–100 percentile scale across 18 natural hazard types, factoring in expected annual loss, social vulnerability, and community resilience. Williamson County's composite score of 85 means its overall natural hazard risk is higher than 85% of US counties.