States › Illinois › Williamson County
Williamson County, Illinois
Recorded hazard history: storm events since 1950, federal disaster declarations since 1953, flood insurance claims since 1978, and FEMA's risk index.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. NCEI storm records through 30 Jun 2026; OpenFEMA declarations refreshed 29 Sep 2026; NFIP claims as of 8 Sep 2026.
The NCEI record lists 892 events for Williamson County, Illinois, between 1950 and 2026; damaging wind account for the largest share.
That is 212.3 events per 100 square miles, above the Illinois figure of 120.2, and 133.4 per 10,000 residents against 52.7 statewide.
26 events fall in the 12 months to 30 Jun 2026. NCEI attributes 13 deaths and 270 injuries to events in the county, with property damage estimated at $498M and crop damage at $3.5M.
FEMA has designated the county in 9 federal disaster declarations since 1953; the most recent is Covid-19 Pandemic (major disaster, 26 Mar 2020).
National Flood Insurance Program policyholders in the county filed 239 claims since 1978, of which 192 were paid, totalling $2.1M (about $11K per paid claim). FEMA counts 141 residential flood policies in force.
FEMA's National Risk Index rates the county's overall risk as "Relatively Moderate" and its expected annual loss as "Relatively Low" ($53M a year across 18 hazards).
2 tropical storm or hurricane tracks in the HURDAT2 record passed within 100 miles of the county's centre at tropical-storm strength or more, 0 of them within 50 miles at hurricane strength.
Compared with Illinois and the United States
| Measure | Williamson County | Illinois | US |
|---|---|---|---|
| Recorded events since 1950 | 892 | 66,722 | 1,977,440 |
| Events per 100 square miles | 212.3 | 120.2 | 56.0 |
| Events per 10,000 residents | 133.4 | 52.7 | 59.6 |
| Events in the last 12 months | 26 | 3,232 | 62,008 |
| Deaths recorded by NCEI | 13 | 1,148 | 26,435 |
| Property damage (NCEI estimates) | $498M | $6.9B | $575B |
| NFIP claims per 1,000 residents | 3.6 | 4.2 | 8.1 |
| Average paid NFIP claim | $11K | $14K | $43K |
| Claims per 100 policies in force, last 10 years | 20.6 | 21.1 | 16.1 |
County-recorded events plus zone-recorded events whose forecast zone is named for the county. State and US rows include events recorded only by forecast zone. Rates use 2021 Census population and land area.
Events by decade
Trend: 669 events in the 20 years to 2025 against 185 in the 20 years before. Reporting practice changed in 1996 and again with automated reports in the 2000s, so decade totals measure the record as much as the weather.
Events by type
Hazard pages exist for hail, tornado, flood, wind and winter where the county has at least 10 recorded events. "Other" covers heavy rain, debris flow, dust, funnel clouds and similar reports.
Largest recorded events
| Date | Event type | Group | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|---|
| 29 May 1982 | Tornado | Tornado | F4 | $250M | — | 10 | 181 | County |
| 22 Jun 1998 | Heat | Heat | — | — | — | 1 | — | Forecast zone |
| 3 Aug 2000 | Flood | Flood | — | — | — | 1 | — | County |
| 23 Dec 2004 | Cold/Wind Chill | Cold | — | — | — | 1 | — | Forecast zone |
| 8 May 2009 | Thunderstorm Wind | Wind | 100 mph | $175M | — | — | 23 | County |
| 19 Nov 1991 | Tornado | Tornado | F3 | $25M | — | — | 16 | County |
| 21 Aug 2017 | Heat | Heat | — | — | — | — | 15 | Forecast zone |
| 18 Dec 1957 | Tornado | Tornado | F4 | $2.5M | — | — | 10 | County |
| 16 May 2025 | Tornado | Tornado | EF4 | $25M | — | — | 7 | County |
| 25 Jul 1997 | Heat | Heat | — | — | — | — | 6 | Forecast zone |
| 3 Aug 2002 | Heat | Heat | — | — | — | — | 6 | Forecast zone |
| 21 Jul 2005 | Heat | Heat | — | — | — | — | 3 | Forecast zone |
| 7 Feb 2011 | Winter Weather | Winter | — | — | — | — | 3 | Forecast zone |
| 30 Jun 2023 | Hail | Hail | 3.00 in | $10M | — | — | — | County |
| 1 Sep 2007 | Drought | Drought | — | — | $3.5M | — | — | Forecast zone |
| 2 May 2002 | Hail | Hail | 2.00 in | $2.0M | — | — | — | County |
| 10 May 1996 | Flash Flood | Flood | — | $1.0M | — | — | — | County |
| 28 Apr 1996 | Flash Flood | Flood | — | $500K | $50K | — | — | County |
| 11 Feb 2008 | Winter Storm | Winter | — | $500K | — | — | — | Forecast zone |
| 14 Sep 2008 | High Wind | Wind | 60 mph | $500K | — | — | — | Forecast zone |
Ranked by deaths, then injuries, then NCEI's damage estimate. Deaths and injuries are NCEI counts (direct plus indirect); no personal details are recorded here.
Federal disaster declarations
| Declared | Number | Type | Incident | Title | Programs |
|---|---|---|---|---|---|
| 26 Mar 2020 | DR-4489 | Major disaster | Biological | Covid-19 Pandemic | Individual assistance, Public assistance |
| 13 Mar 2020 | EM-3435 | Emergency | Biological | Covid-19 | Public assistance |
| 7 Jun 2011 | DR-1991 | Major disaster | Severe Storm | Severe Storms And Flooding | Individual assistance, Public assistance |
| 2 Jul 2009 | DR-1850 | Major disaster | Severe Storm | Severe Storms, Flooding, And Tornadoes | Public assistance |
| 7 Sep 2005 | EM-3230 | Emergency | Hurricane | Hurricane Katrina Evacuation | Public assistance |
| 1 Feb 2005 | EM-3199 | Emergency | Snowstorm | Record/Near Record Snow | Public assistance |
| 21 May 2002 | DR-1416 | Major disaster | Tornado | Severe Storms, Tornadoes And Flooding | Individual assistance |
| 6 May 1996 | DR-1112 | Major disaster | Severe Storm | Severe Storms And Flooding | Individual assistance, Public assistance |
| 5 Jun 1982 | DR-660 | Major disaster | Tornado | Severe Storms & Tornadoes | Individual assistance, Public assistance |
Declarations in which FEMA designated this county, from the OpenFEMA Disaster Declarations Summaries (v2). DR: major disaster; EM: emergency; FM: fire management assistance. Programs show whether individual or public assistance was made available.
Flood insurance claims
| Year of loss | Claims | Paid claims | Amount paid | Average paid |
|---|---|---|---|---|
| 2026 | 3 | 0 | $0 | — |
| 2023 | 3 | 2 | $59,086 | $29,543 |
| 2022 | 1 | 0 | $0 | — |
| 2021 | 1 | 1 | $3,863 | $3,863 |
| 2018 | 1 | 1 | $1,944 | $1,944 |
| 2017 | 20 | 16 | $326,612 | $20,413 |
| 2011 | 6 | 2 | $8,174 | $4,087 |
| 2010 | 2 | 2 | $22,983 | $11,491 |
| 2009 | 6 | 5 | $68,300 | $13,660 |
| 2008 | 33 | 29 | $382,465 | $13,188 |
| 2005 | 3 | 2 | $7,299 | $3,650 |
| 2002 | 1 | 1 | $147 | $147 |
| 2000 | 2 | 0 | $0 | — |
| 1999 | 6 | 4 | $53,724 | $13,431 |
| 1998 | 4 | 4 | $28,998 | $7,250 |
| 1997 | 1 | 1 | $499 | $499 |
| 1996 | 38 | 35 | $467,820 | $13,366 |
| 1993 | 6 | 6 | $63,618 | $10,603 |
| 1991 | 9 | 7 | $113,265 | $16,181 |
| 1990 | 10 | 8 | $135,783 | $16,973 |
| 1989 | 4 | 1 | $132 | $132 |
| 1985 | 6 | 5 | $20,614 | $4,123 |
| 1984 | 10 | 9 | $78,741 | $8,749 |
| 1983 | 25 | 21 | $119,771 | $5,703 |
| 1982 | 34 | 27 | $136,797 | $5,067 |
OpenFEMA NFIP claims (v3, as of 8 Sep 2026), aggregated by year of loss; amounts are building, contents and increased-cost-of-compliance payments as recorded. Repetitive-loss counts from the NFIP Multiple Loss Properties file (2 Aug 2026); policies in force from the NFIP Residential Penetration Rates file (3 Aug 2026).
National Risk Index
| Hazard (NRI) | Risk rating | Expected annual loss |
|---|---|---|
| Earthquake | $19,636,157 | |
| Inland flooding | $11,716,965 | |
| Strong wind | $7,496,108 | |
| Cold wave | $5,009,454 | |
| Tornado | $3,615,030 | |
| Heat wave | $2,880,138 | |
| Hail | $720,700 | |
| Ice storm | $428,462 | |
| Lightning | $409,490 | |
| Winter weather | $364,090 | |
| Drought | $178,366 | |
| Hurricane | $39,083 | |
| Landslide | $13,054 | |
| Wildfire | $4,288 |
FEMA National Risk Index, December 2025 release. Ratings are FEMA's relative comparison of counties; expected annual loss is FEMA's modelled estimate of average yearly building, population and agriculture loss. See how to read the NRI.
Hurricane and tropical storm passes
| Storm | Year | Closest approach | Max wind while within 100 mi |
|---|---|---|---|
| Unnamed Atlantic storm | 1941 | 75 mi | 40 mph |
| Unnamed Atlantic storm | 1915 | 10 mi | 40 mph |
HURDAT2 best-track positions at tropical-storm strength (34 kt) or more, measured from the county's Census centre point; through the 2025 season. Distance from a track is not the same as the extent of the storm's wind, rain or surge.
ZIP codes with flood claims
ZIP codes whose NFIP claims carry this county's code, with the number of claims. Five or more claims are needed for a ZIP page to be indexed.
Questions and answers
How often does it hail in Williamson County, IL?
NCEI records 120 hail events in Williamson County since 1950, in 30 different years; that is about 1.6 recorded events a year. 21 reports were golf-ball size (1.75 in) or larger.
Has Williamson County had a tornado?
Yes. NCEI records 22 tornadoes in Williamson County since 1950, 7 of them rated (E)F2 or stronger. Tornado deaths recorded: 10.
When was the last federal disaster declaration for Williamson County?
26 Mar 2020: Covid-19 Pandemic, a major disaster declaration for biological. The county appears in 9 declarations since 1953.
How many flood insurance claims have been filed in Williamson County, and how much was paid?
239 NFIP claims since 1978, 192 of them paid, for $2.1M in total. FEMA publishes these figures redacted and aggregated; individual properties are not identified.
Is Williamson County in the National Risk Index's high-risk band?
FEMA's National Risk Index (December 2025) rates the county "Relatively Moderate" for overall risk, "Relatively Low" for expected annual loss, "Relatively Moderate" for social vulnerability and "Relatively High" for community resilience. These ratings are FEMA's relative comparison across all US counties.
How does Williamson County compare with the rest of Illinois?
212.3 recorded events per 100 square miles against 120.2 statewide, and 3.6 NFIP claims per 1,000 residents against 4.2. The comparison table on this page shows each measure beside the state and national figures.
Provenance
Storm events: NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026 (public domain). Declarations: OpenFEMA DisasterDeclarationsSummaries v2, refreshed 29 Sep 2026. Flood claims: OpenFEMA NfipClaims v3 as of 8 Sep 2026; NfipMultipleLossProperties v1 (2 Aug 2026); NfipResidentialPenetrationRates v1 (3 Aug 2026). Risk index: FEMA National Risk Index, December 2025. Hurricane tracks: NHC HURDAT2 through 2025. Population and area: US Census Bureau, 2021 vintage. Built 30 Sep 2026; see the methodology and corrections pages. Hazard hubs: Hail · Tornado · Flood · Wind · Winter.