Johnson County, Illinois: Natural Disaster Risk and History
Johnson County, Illinois has a Relatively Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 51.1 out of 100, higher than about 51% of US counties, with earthquakes, heat waves and strong winds scoring highest of its 18 hazards and $12 million a year in expected losses.
OpenFEMA lists 5 federal disaster declarations that included Johnson County since 1973, not counting 2 for COVID-19; the latest is DR-1826-IL (Severe Winter Storm, declared 2 March 2009). NOAA's Storm Prediction Center recorded 20 tornadoes touching Johnson County from 1950 to 2025.
Live weather alerts for Illinois All official warnings Latest FEMA declarations
Population 13,301 Buildings worth $3.6 billion Area 352 sq mi Risk rank in Illinois 58 of 102 FIPS 17087
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Earthquake | Relatively Moderate | 91.0 | $4.4 million | about once every 100 years | — |
| Heat wave | Relatively Low | 68.9 | $623,348 | about 11 a year | 145 |
| Strong wind | Relatively Moderate | 68.8 | $676,066 | about 4 a year | 154 |
| Ice storm | Relatively Moderate | 68.4 | $145,280 | about once every 1.1 years | 62 |
| Hail | Relatively Low | 66.5 | $346,306 | about 3.2 a year | 122 |
| Winter weather | Relatively Moderate | 64.6 | $76,178 | about 7.5 a year | 142 |
| Cold wave | Relatively Low | 64.0 | $1.2 million | about 1.1 a year | 21 |
| Tornado | Relatively Low | 56.0 | $1.1 million | about once every 3.3 years | 16 |
| Drought | Relatively Low | 52.5 | $124,558 | about 4 a year | 147 |
| Landslide | Very Low | 44.0 | $636 | about once every 1.2 years | — |
| Hurricane | Very Low | 38.1 | $19,186 | about once every 46 years | 6 |
| Inland flooding | Relatively Low | 37.9 | $3.2 million | about once every 1.2 years | 23 |
| Lightning | Relatively Low | 33.8 | $91,026 | about 55 a year | 63,326 strikes |
| Wildfire | Very Low | 11.3 | $2,633 | 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 5
Most common: Severe Storm 1, Hurricane 1, Snowstorm 1, Tornado 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 1 | Flood |
| 2000s | 4 | Severe Storm, Hurricane, Snowstorm, Tornado |
The last 5
Widest declarations that included Johnson 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 20
| Tornadoes touching the county | 20 |
|---|---|
| Strongest-rated | (E)F3 ×2 |
| Peak month | May (6) |
| Deadliest | 28 Apr 2002, F3, 19.3 mi path, 1 killed, 10 injured |
| Longest path | 14 Apr 1972, F2, 30.9 mi path, 0 killed, 9 injured |
| Most recent | 2 Apr 2025, EF2, 6.2 mi path |
| Deaths / injuries on those paths | 1 / 26 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 4 | 5 | 9 | 2 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 1 | 0 | 3 | 1 | 2 | 6 | 3 | 4 |
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 Johnson County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Johnson County (this page) | — | Relatively Low | 51.1 | Earthquake |
| Pope County | 29 km | Very Low | 14.9 | Earthquake |
| Williamson County | 30 km | Relatively Moderate | 85.8 | Strong wind |
| Massac County | 31 km | Relatively Low | 61.6 | Earthquake |
| Union County | 33 km | Relatively Low | 55.4 | Earthquake |
| Pulaski County | 34 km | Relatively Low | 49.0 | Earthquake |
Nearest by distance between county centres. Every county in Illinois, ranked.
Vulnerability and resilience
| Social vulnerability | Very High 82.0 |
|---|---|
| Community resilience | Relatively Moderate 47.6 |
| Community risk factor | 1.45 |
| Expected annual loss, all hazards | $12 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 Johnson County's main hazards
- Right now: National Weather Service alerts for Illinois · all official warnings on Global Incident Tracker.
- Earthquake: Earthquakes today · Earthquake safety guide
- Heat wave: Heatstroke warning signs
- Strong wind: Power outages now
- 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 Johnson County
What natural disasters is Johnson County, Illinois most at risk from?
Johnson County, Illinois has a Relatively Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 51.1 out of 100, higher than about 51% of US counties, with earthquakes, heat waves and strong winds scoring highest of its 18 hazards and $12 million a year in expected losses.
How many federal disaster declarations has Johnson County had?
OpenFEMA lists 5 federal disaster declarations that included Johnson County since 1973, not counting 2 for COVID-19; the latest is DR-1826-IL (Severe Winter Storm, declared 2 March 2009). Another 2 Illinois declarations were made statewide without a county list.
How many tornadoes have hit Johnson County?
NOAA's Storm Prediction Center recorded 20 tornadoes touching Johnson County from 1950 to 2025. The deadliest: 28 Apr 2002, F3, 19.3 mi path, 1 killed, 10 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.