Williamson County, IL
FEMA National Risk Index scores, disaster declarations & hazard data
Williamson County has experienced 9 federally declared disasters since 1982, most recently Covid-19 in 2020. Its overall natural hazard risk is rated Relatively Moderate — near the middle compared to other US counties.
Williamson County's highest-rated hazards are strong wind, earthquake, and heat wave, with its top risk rated "Very High" by FEMA's National Risk Index. NOAA records 131 storm events in the county over the past decade.
Past disasters & FEMA designations
A federal disaster declaration officially designates a county for FEMA disaster assistance. Williamson County has been designated in 9 declarations since 1982, covering 5 disaster types including severe storm (3), biological (2), tornado (2).
| Year | Type | Event name |
|---|---|---|
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2011 | Severe Storm | Severe Storms And Flooding |
| 2009 | Severe Storm | Severe Storms, Flooding, And Tornadoes |
| 2005 | Snowstorm | Record/Near Record Snow |
| 2005 | Hurricane | Hurricane Katrina Evacuation |
| 2002 | Tornado | Severe Storms, Tornadoes And Flooding |
| 1996 | Severe Storm | Severe Storms And Flooding |
| 1982 | Tornado | Severe Storms & Tornadoes |
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 | 14.2 | 0 | 0 | — |
| Inland Flooding | Relatively Low | 69.9 | 27 | 0 | $260K |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Relatively Moderate | 96.3 | — | — | — |
| Heat Wave | Relatively Moderate | 90.7 | 47 | 0 | — |
| Tornado | Relatively Moderate | 80.3 | 11 | 0 | $25.8M |
| Hurricane | Very Low | 44.5 | 0 | 0 | — |
| Hail | Relatively Moderate | 78.3 | 46 | 0 | $10.0M |
| Strong Wind | Very High | 99.1 | 0 | 0 | — |
| Winter Weather | Relatively High | 89.8 | 0 | 0 | — |
| Ice Storm | Relatively Moderate | 81.9 | — | — | — |
| Cold Wave | Relatively Moderate | 86.9 | — | — | — |
| Lightning | Relatively Moderate | 67.7 | 0 | 0 | — |
| Drought | Relatively Low | 54.2 | 0 | 0 | — |
| Landslide | Relatively Low | 79.3 | 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 39th percentile (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 | 39th | Low |
| Socioeconomic status | 30th | Low |
| Household characteristics | 62nd | Moderate |
| Racial & ethnic minority status | 34th | Low |
| Housing type & transportation | 46th | 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 | 31st | Relatively Low |
| Risk to homes | 29th | Relatively Low |
| Buildings in direct exposure zone | 50.4% | — |
NOAA tracked 131 weather events in this county over 2016–2025: 63 in 2016–20 vs 68 in 2021–25 (+8% — relatively stable).
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, Illinois are strong wind, earthquake, and heat wave. 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 9 federal disaster declarations since 1982, including declarations in 2020. The most common disaster type on record is severe storm (3 declarations).
Has Williamson County had any FEMA disaster declarations in 2024, 2025, or 2026?
No federal disaster declarations have been recorded for Williamson County since the start of 2024. Its most recent declaration on record is Covid-19 in 2020.
How does Williamson County's natural hazard risk compare to nearby counties?
Among neighboring counties, Jackson County, IL has the highest overall natural hazard risk (Relatively Moderate) and Pope County, IL has the lowest (Very 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 86 means its overall natural hazard risk is higher than 86% of US counties.