Home › Illinois › Johnson County

Johnson County, Illinois

Natural disaster risk, federal disaster history and flood insurance facts.

Relatively Low overall risk
58th of 102highest risk in Illinois
$12Mexpected losses a year
5federal declarations
1 in 1000homes with flood insurance
Photo: U.S. Geological Survey, CC0

Johnson County, Illinois has a relatively low overall risk from natural hazards in FEMA's National Risk Index. Its risk score is higher than 51% of US counties. It ranks 58th of 102 counties in Illinois. The costliest hazards here are earthquakes, inland flooding and cold waves. FEMA estimates about $12 million a year in expected losses, or roughly $898 per resident. Since 1973 it has been included in 5 federal disaster or emergency declarations for natural events (3 major disasters). The most recent was in March 2009 (severe winter storm). Only 5 homes here carry federal flood insurance.

FEMA National Risk Index December 2025; OpenFEMA declarations to Nov 6, 2026; NFIP records. Updated November 6, 2026.

Top risks in Johnson County

Earthquake

Moderate
$4.4 million a yearExpected losses. Damaging events about once every 100 years.
  • Ask whether an older house is bolted to its foundation.
  • Consider separate earthquake insurance where risk is high.
$3.2 million a yearExpected losses. Damaging events about once a year.
  • Check the FEMA flood map for your address, and ask the seller or landlord about past flooding.
  • Price a flood policy now. Most new federal policies take 30 days to start.
$1.2 million a yearExpected losses. Damaging events about once a year.
  • Insulate pipes in outside walls, crawl spaces and garages.
  • Know how to shut off the main water valve.
HazardRatingScoreExpected loss a year
EarthquakeModerate91.0
$4M
Inland floodingLow37.9
$3M
Cold waveLow64.0
$1M
TornadoLow56.0
$1M
Strong windModerate68.8
$676K
Heat waveLow68.9
$623K
HailLow66.5
$346K
Ice stormModerate68.4
$145K
DroughtLow52.5
$125K
LightningLow33.8
$91K
Winter weatherModerate64.6
$76K
HurricaneVery Low38.1
$19K
WildfireVery Low11.3
$3K
LandslideVery Low44.0
$636

Scores are percentiles: a score of 90 means higher risk than about 90% of US counties for that hazard. Hazards FEMA does not rate here are left out. Social vulnerability is very high and community resilience is relatively moderate in FEMA's measures.

Federal disaster history

Recent disasters nationwide ›

Declarations by decade

Federal declarations for natural events that included Johnson County. 2020s bar runs to November 2026.

By type

Flood1
Tornado1
Snowstorm1
Hurricane1
Severe Storm1

Most recent

Mar 2, 2009Severe Winter StormMajor disaster
Sep 7, 2005Hurricane Katrina EvacuationEmergency
Feb 1, 2005Record/Near Record SnowEmergency
May 21, 2002Severe Storms, Tornadoes and FloodingMajor disaster
Apr 26, 1973Severe Storms & FloodingMajor disaster

Illinois also had 2 statewide declarations that did not name single counties.

Storm history since 1957

Tornado risk by county ›

The National Weather Service has logged 233 storm reports in Johnson County since 1957, with 1 death and 24 injuries and about $16 million in reported damage. The strongest on record here was an EF3 tornado on May 26, 2024 near Goreville.

21tornadoes
88hail reports, largest 3 inches
96damaging thunderstorm winds
24floods and flash floods

Strongest tornadoes

DateStrengthNearHurt / killed
May 26, 2024EF3Goreville1 / 0
Apr 28, 2002F2Cypress2 / 0
Mar 15, 2025EF2Boles0 / 0
Oct 18, 2004F2Goreville2 / 0
Apr 28, 2002F2Vienna2 / 0

Most damaging storms

DateTypeNearDamage
May 23, 2000HailGoreville$7M
Apr 28, 2002TornadoCypress$3M
Mar 18, 2008FloodGoreville$2M
Mar 15, 2025TornadoBoles$1M
May 26, 2024TornadoGoreville$750K
Oct 18, 2004TornadoGoreville$500K

Source: NOAA Storm Events Database, county-based reports through Apr 27, 2026. Tornado records start in 1950, hail and wind in 1955, and floods and other storm types in 1996, so older decades undercount. Damage is in dollars of the year it happened and is often an estimate. Winter storms, heat and hurricanes are logged by forecast zone, not county, so they are not counted here.

Flood insurance in Johnson County

Check your address flood zone ›
0.1%of homes have federal flood insurance (5 policies)
0%of homes in mapped high-risk flood zones are insured
$19,821paid on 3 flood claims since 1978
2008costliest year, with $12,124 paid

National Flood Insurance Program (NFIP) records only; private flood policies are not included. Home counts as of Aug 3, 2026. Since 2021 NFIP prices each home separately under Risk Rating 2.0, so your price depends on the building, not the county. Ask an agent for a quote.

Homes in Johnson County

$160,500median home value (Illinois $263,300, US $332,700)
1985median year homes were built (Illinois 1971, US 1980)
44%of homes built before 1980, before many modern wind, quake and flood building rules
26.5%of homes are mobile homes, which are the least safe in tornadoes and high winds

Older homes and mobile homes usually suffer more damage in storms, floods and earthquakes, and can cost more to insure. If you are buying, ask about roof age, foundation bolting and any retrofits. Source: US Census Bureau, American Community Survey 2020 to 2024 5-year estimates; 5,541 housing units.

Compare in Illinois

All 102 ›
Largest countiesOverall riskTop hazard
Cook CountyVery HighInland flooding
DuPage CountyHighInland flooding
Lake CountyHighInland flooding
Will CountyHighInland flooding
Kane CountyHighInland flooding
McHenry CountyModerateInland flooding
Winnebago CountyModerateInland flooding
Madison CountyModerateInland flooding

Neighboring counties

CountyOverall riskDeclarations
Williamson CountyModerate7
Saline CountyLow7
Union CountyLow13
Massac CountyLow10
Pulaski CountyLow12
Pope CountyVery Low10

Common questions about Johnson County

What is the biggest natural hazard in Johnson County?

Earthquake has the highest expected yearly losses in Johnson County, about $4.4 million a year in FEMA's estimate. Inland flooding is second at $3.2 million.

How many federal disasters has Johnson County had?

Johnson County has been included in 5 federal disaster or emergency declarations for natural events since 1973, including 3 major disasters. The most recent was Severe Winter Storm in March 2009.

Is Johnson County a high-risk place to live?

Its overall rating is Relatively Low, 58th highest of 102 in Illinois. A county rating covers the whole area. Risk at one address can be much higher or lower, so check the FEMA flood map and ask about the home's history.

Do I need flood insurance in Johnson County?

Standard home insurance does not cover flooding. About 1 in 1000 homes in Johnson County has federal flood insurance. Lenders require it in mapped high-risk zones, but many flood claims come from outside those zones.

How many tornadoes has Johnson County had?

NOAA records list 21 tornadoes in Johnson County since 1950. The strongest was an EF3 tornado on May 26, 2024 near Goreville. The weather service has also logged 88 hail reports and 24 floods here.

Sources: FEMA National Risk Index (December 2025), OpenFEMA Disaster Declarations Summaries, and NFIP policy and claims data. Hazard Compass is independent and not affiliated with FEMA. These figures describe the whole county, not a single property, and are not insurance or safety advice. Report a problem.