Williamson County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Williamson County: 10.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every storm within 100 miles

1. Tropical storms and hurricanes (34 kt or more, still tropical) at closest approach. Post-tropical remnants with gale-force winds are listed but not counted. Direct: track within 50 miles; near: within 100 miles. Distance is measured to the county boundary for counties and to the city centre for cities, using positions interpolated hourly between HURDAT2 fixes.

National Hurricane Center HURDAT2, 1851 to 2025.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

More event types since 1996

Costliest events since 1996

1. May 8, 2009Thunderstorm Wind$175 million
   National Weather Service narrative

   Widespread wind damage occurred countywide. Extensive tree and power line damage resulted in power outages up to several days long. Many power poles were snapped. Countywide, efforts to restore power were complicated by swampy fields, mud, and downed trees. Ninety-five percent of the county was without power at the peak of the outages. Numerous permanent structures were damaged, including major businesses in downtown Marion and Herrin. A total of 33 homes were heavily damaged or destroyed. It is estimated that over 10,000 homes in the county received minor damage (less than 50,000 dollars per house). Gas leaks were common. Most communication by phone was impossible, including cell…

2. May 16, 2025Tornado$25.0 million
   National Weather Service narrative

   A violent EF-4 tornado with peak winds of 190 mph impacted southern Williamson County, IL, during the early evening hours of Friday, May 16, 2025. The tornado began near the intersection of Spillway Road and Grassy Road doing mainly tree damage. As it moved eastward, the tornado intensified as it approached I-57. The tornado strengthened to EF-3 levels, where it removed the roofs of several homes of the staff of the U.S. Penitentiary just south of the main prison complex. The tornado debarked, and reduced to stubs, numerous trees adjacent to I-57. Multiple videos of this tornado were taken around the time it crossed I-57. The tornado continued at EF-3 strength as it damaged homes…

3. Jun 30, 2023Hail$10.0 million
   National Weather Service narrative

   Giant hail occurred in a swath of Williamson County along Illinois Route 13. The swath of large hail began near the Marion/Williamson County airport, just east and southeast of Crainville. Hail slightly larger than baseballs pounded the area in the immediate vicinity of the Marion/Williamson County Regional Airport. Hail damage was reported to planes at the airport, including broken windows. Numerous vehicles were damaged by hail from quarter size to golf-ball size. Hail damage occurred at the baseball stadium near Interstate 57 at Route 13. There was major damage to multiple vehicles at a car dealership on Route 13 between the Marion airport and the downtown Marion area. The…

4. May 2, 2002Hail$2.0 million
   National Weather Service narrative

   A severe thunderstorm produced very large hail as it moved east across Jackson and Williamson Counties. The largest hail, which was between golf ball and tennis ball size, occurred in a swath parallel to and just south of Illinois Route 13. Large hail up to half-dollar size was reported as far north as Desoto and Johnston City. The hailstorm clipped the northeast corner of Johnson County, producing hail up to golf ball size. Extensive damage occurred to vehicles and some building exteriors. Windshields were broken. One insurance company reported 66 auto and 81 property damage claims.

5. May 10, 1996Flash Flood$1.0 million
   National Weather Service narrative

   Very heavy rains caused many roads to become impassable across the county. This rain compounded the flood damage that occurred in late April. A cooperative observer in Marion reported 7.33 inches of rain, most of which fell in a three hour period. Between 60 and 70 residents of a nursing home in Marion were evacuated. The county was declared a federal disaster area. Nearly 100,000 dollars damage occurred to county roads. Several residents were evacuated. Some people were trapped in their cars, which were stalled in up to 4 feet of water. The damage total listed above is for all the flood events since April 28. A total of at least 41 businesses and 40 homes received water damage.…

6. Jan 26, 2009Winter Storm, Williamson$500,000
   National Weather Service narrative

   A prolonged, major winter storm dumped 6 to 10 inches of sleet and snow north of a line from East Cape Girardeau through Vienna to the confluence of the Wabash and Ohio Rivers. This resulted in at least two dozen roof collapses and very difficult driving conditions. South of that line, at least one inch of ice accumulated, with locally around 1.5 inches of ice. This resulted in a federal disaster declaration due to widespread tree damage and power outages. Virtually 100 percent of Massac County in the southern tip of the state was without power. The vast majority of nearby Alexander, Pulaski, Pope, Hardin, and southern Johnson Counties lost power. A major 161,000 volt transmission…

7. Feb 11, 2008Winter Storm, Williamson$500,000
   National Weather Service narrative

   Low pressure developed over the southern Plains, spreading widespread heavy precipitation across southern Illinois. At the same time, high pressure over the upper Ohio Valley produced a cold easterly wind flow. The result was a crippling ice storm. Around one inch of ice caused extensive damage across far southern Illinois, along and south of a line from Carbondale and Marion to Harrisburg and Carmi. Many of those same areas received three to six inches of sleet and snow. The most destructive icing occurred in an east to west band across Union, Johnson, Massac, and Pope Counties. The state designated most counties in southern Illinois as a disaster area. Numerous trees and power…

8. Apr 28, 1996Flash Flood$500,000
   National Weather Service narrative

   This was the first of two major flash flood events. The second occurred on May 10. The combined effect of the two events prompted a federal disaster declaration for the county. Low-lying areas were evacuated, most streets were closed, and a dike collapsed in Marion's flood control project. The dike, which broke about half a mile south of Marion, flooded a farm field and three acres of land. Illinois Route 37 was closed near Johnston City.

9. Sep 14, 2008High Wind, Williamson$500,000
   National Weather Service narrative

   Frequent wind gusts from 60 to nearly 70 mph caused considerable damage in southern Illinois. The low pressure center that was the remnant of Hurricane Ike raced northeast at 40 to 50 mph across Missouri and Illinois. The center passed between Carbondale and St. Louis on its way toward the northeastern states. The rapid speed of the low pressure system contributed to this high wind event.||Considerable tree damage occurred. Trees were uprooted, and very large limbs were broken. Some trees fell on homes, outbuildings, and vehicles. Fewer than a dozen homes in each county were damaged by falling trees. Others fell on commercial and public buildings. Numerous trees or limbs fell on…

10. Mar 18, 2008Flood$375,000
    National Weather Service narrative

    In Marion, firefighters used boats to rescue 13 residents of the city's housing project. Water was up to a foot deep in some apartments. Five stranded motorists were rescued by Marion firefighters. A total of 21 persons were rescued by boat by firefighters in the city of Marion. At least a few vehicles were submerged up to their headlights. Victims were transported to a Red Cross shelter. A Marion official stated this was the worst flood since May of 1996, before the flood control project was completed. Many streets were underwater, including the main access road to Marion High School. An SUV was stranded in floodwaters. In Johnston City, most roadways were closed. A bridge was…

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

113°FAug 9, 1930

All-time low

−25°FJan 11, 1977

Warmest night

84°FAug 6, 1900

Coldest day

−3°FDec 23, 1989

Wettest day

6.90 inJun 17, 2000

Snowiest day

10.0 inFeb 26, 1979

Hottest year

1921mean 60.6°F

Coldest year

1979mean 52.4°F

Wettest year

194574.50 in

Driest year

190121.58 in

Snowiest season

50.4 in1911-12

Station Carbondale Sewage Plt (USC00111265), 390 ft elevation, 10.5 miles from the population centre. Daily records from 1898 to October 27, 2026; 97.9% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USC00111265.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.