St. Clair County, Illinois: Natural Disaster Risk and History
St. Clair County, Illinois has a Relatively High natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 94.9 out of 100, higher than about 94% of US counties, with heat waves, earthquakes and hail scoring highest of its 18 hazards and $175 million a year in expected losses.
OpenFEMA lists 17 federal disaster declarations that included St. Clair County since 1968, not counting 2 for COVID-19; the latest is DR-4819-IL (Severe Storms, Tornadoes, Straight-Line Winds, and Floodng, declared 20 September 2024). NOAA's Storm Prediction Center recorded 59 tornadoes touching St. Clair County from 1950 to 2025.
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Population 257,200 Buildings worth $62 billion Area 681 sq mi Risk rank in Illinois 5 of 102 FIPS 17163
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Heat wave | Relatively High | 98.1 | $15 million | about 15 a year | 154 |
| Earthquake | Relatively Moderate | 98.0 | $51 million | about once every 157 years | — |
| Hail | Relatively High | 97.6 | $5.1 million | about 5.2 a year | 198 |
| Cold wave | Relatively High | 96.4 | $15 million | about 1.4 a year | 27 |
| Tornado | Relatively High | 95.5 | $13 million | about once every 1.7 years | 46 |
| Inland flooding | Relatively High | 94.5 | $72 million | about 1.8 a year | 50 |
| Lightning | Relatively High | 93.7 | $1.6 million | about 52 a year | 488,869 strikes |
| Ice storm | Relatively High | 91.0 | $1.0 million | about 1.4 a year | 94 |
| Winter weather | Relatively High | 87.2 | $332,859 | about 9 a year | 171 |
| Landslide | Relatively Low | 84.3 | $27,606 | about once every 2.2 years | — |
| Drought | Relatively Low | 61.4 | $313,995 | about 1.7 a year | 42 |
| Strong wind | Relatively Moderate | 54.0 | $627,349 | about 6.2 a year | 234 |
| Hurricane | Very Low | 34.9 | $21,007 | about once every 79 years | 4 |
| Wildfire | Very Low | 15.1 | $5,162 | rarer than once in 1,000 years | — |
| Avalanche | Not Applicable | — | — | — | — |
| Coastal flooding | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 17
Most common: Flood 8, Severe Storm 5, Tornado 2, Severe Ice Storm 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1960s | 2 | Flood, Tornado |
| 1970s | 2 | Flood ×2 |
| 1980s | 2 | Flood, Severe Storm |
| 1990s | 4 | Severe Storm ×3, Flood |
| 2000s | 4 | Severe Storm, Severe Ice Storm, Hurricane, Tornado |
| 2010s | 1 | Flood |
| 2020s | 2 | Flood ×2 |
The last 10
Widest declarations that included St. Clair County
- Hurricane Katrina Evacuation (2005, EM-3230-IL): 102 Illinois counties designated.
- Severe Storms, Tornadoes and Flooding (2002, DR-1416-IL): 68 Illinois counties designated.
- Severe Storms & Flooding (1973, DR-373-IL): 52 Illinois counties designated.
Named storms in its declarations: Hurricane Katrina (2005).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. Illinois also had 2 statewide declarations with no county list.
Tornado record since 1950 59
| Tornadoes touching the county | 59 |
|---|---|
| Strongest-rated | (E)F3 ×3 |
| Peak month | April (17) |
| Deadliest | 15 May 1968, F3, 2 mi path, 4 killed, 60 injured |
| Longest path | 3 May 1958, F1, 75.9 mi path |
| Most recent | 20 Apr 2025, EF0, 0.8 mi path |
| Deaths / injuries on those paths | 6 / 106 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 23 | 19 | 14 | 3 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 11 | 5 | 2 | 5 | 10 | 8 | 6 | 12 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How St. Clair County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| St. Clair County (this page) | — | Relatively High | 94.9 | Heat wave |
| Monroe County | 30 km | Very Low | 41.9 | Heat wave |
| St. Louis City, MO | 33 km | Relatively High | 98.7 | Heat wave |
| Madison County | 40 km | Relatively Moderate | 93.4 | Heat wave |
| Clinton County | 47 km | Relatively Low | 65.6 | Earthquake |
| Washington County | 47 km | Relatively Low | 55.2 | Earthquake |
Nearest by distance between county centres. Every county in Illinois, ranked.
Vulnerability and resilience
| Social vulnerability | Relatively Low 37.8 |
|---|---|
| Community resilience | Relatively High 74.9 |
| Community risk factor | 1.03 |
| Expected annual loss, all hazards | $175 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for St. Clair County's main hazards
- Right now: National Weather Service alerts for Illinois · all official warnings on Global Incident Tracker.
- Heat wave: Heatstroke warning signs
- Earthquake: Earthquakes today · Earthquake safety guide
- Hail: Weather alerts for Illinois
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets 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).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. 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).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about St. Clair County
What natural disasters is St. Clair County, Illinois most at risk from?
St. Clair County, Illinois has a Relatively High natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 94.9 out of 100, higher than about 94% of US counties, with heat waves, earthquakes and hail scoring highest of its 18 hazards and $175 million a year in expected losses.
How many federal disaster declarations has St. Clair County had?
OpenFEMA lists 17 federal disaster declarations that included St. Clair County since 1968, not counting 2 for COVID-19; the latest is DR-4819-IL (Severe Storms, Tornadoes, Straight-Line Winds, and Floodng, declared 20 September 2024). Another 2 Illinois declarations were made statewide without a county list.
How many tornadoes have hit St. Clair County?
NOAA's Storm Prediction Center recorded 59 tornadoes touching St. Clair County from 1950 to 2025. The deadliest: 15 May 1968, F3, 2 mi path, 4 killed, 60 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.