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Mercer County, Illinois

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

Very Low overall risk
97th of 102highest risk in Illinois
$7Mexpected losses a year
13federal declarations
1 in 500homes with flood insurance
Photo: U.S. Geological Survey, public domain

Mercer County, Illinois has a very low overall risk from natural hazards in FEMA's National Risk Index. Its risk score is lower than 91% of US counties. It ranks 97th of 102 counties in Illinois. The costliest hazards here are inland flooding, strong wind and drought. FEMA estimates about $6.9 million a year in expected losses, or roughly $443 per resident. Since 1965 it has been included in 13 federal disaster or emergency declarations for natural events (10 major disasters). The most recent was in September 2019 (severe storms and flooding). Only 15 homes here carry federal flood insurance. Since 1978, federal flood insurance has paid about $1.4 million on 61 claims here, including $769,000 for floods in 1993.

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

Top risks in Mercer County

$2 million a yearExpected losses. Damaging events about 2 times 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.

Strong wind

Moderate
$1.2 million a yearExpected losses. Damaging events about 6 times a year.
  • Secure outdoor furniture and trash bins before storms.
  • Have trees near the house checked.

Drought

Moderate
$907,319 a yearExpected losses. Damaging events about 8 times a year.
  • Check local water restrictions.
  • Choose drought-tolerant plants.
HazardRatingScoreExpected loss a year
Inland floodingVery Low9.2
$2M
Strong windModerate61.6
$1M
DroughtModerate71.5
$907K
Cold waveLow33.4
$777K
Heat waveLow48.5
$551K
LightningModerate58.1
$492K
TornadoVery Low22.5
$467K
Ice stormModerate66.3
$285K
HailVery Low29.5
$182K
EarthquakeVery Low24.7
$69K
Winter weatherLow26.9
$40K
LandslideLow68.1
$8K
HurricaneVery Low11.3
$4K
WildfireVery Low1.1
$719

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 low and community resilience is very high in FEMA's measures.

Federal disaster history

Recent disasters nationwide ›

Declarations by decade

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

By type

Flood7
Snowstorm3
Tornado1
Hurricane1
Severe Storm1

Most recent

Sep 19, 2019Severe Storms and FloodingMajor disaster
May 10, 2013Severe Storms, Straight-Line Winds, and FloodingMajor disaster
Mar 17, 2011Severe Winter Storm and SnowstormMajor disaster
Jun 24, 2008Severe Storms and FloodingMajor disaster
Sep 7, 2005Hurricane Katrina EvacuationEmergency
May 9, 2001FloodingMajor disaster
Jan 8, 1999Il-Winter Storm 1/1/99Emergency
Jul 9, 1993Severe Storms & FloodingMajor disaster
Jan 16, 1979Blizzards & SnowstormsEmergency
Jun 10, 1974Severe Storms & FloodingMajor disaster
Show all 13
Apr 26, 1973Severe Storms & FloodingMajor disaster
Jun 6, 1969FloodingMajor disaster
Apr 25, 1965Tornadoes, Severe Storms & FloodingMajor disaster

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

Storm history since 1952

Tornado risk by county ›

The National Weather Service has logged 334 storm reports in Mercer County since 1952, with 1 death and 6 injuries and about $37.8 million in reported damage. The strongest on record here was an F3 tornado on August 15, 1978.

45tornadoes
96hail reports, largest 2.5 inches
136damaging thunderstorm winds
48floods and flash floods

Strongest tornadoes

DateStrengthNearHurt / killed
Aug 15, 1978F3–0 / 0
Jun 14, 1974F3–1 / 0
Apr 21, 1973F2–0 / 0
Jun 18, 1998F2Seaton0 / 0
Apr 13, 2006F2Matherville0 / 0

Most damaging storms

DateTypeNearDamage
Jul 20, 2003Thunderstorm WindCountywide$13M
Apr 30, 2003Flash FloodCountywide$10M
May 13, 2010Flash FloodEliza$5M
Apr 21, 1973Tornado–$3M
Apr 30, 2003HailNew Boston$500K
Apr 30, 2003TornadoAledo$500K

Source: NOAA Storm Events Database, county-based reports through Jun 17, 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 Mercer County

Check your address flood zone ›
0.2%of homes have federal flood insurance (15 policies)
13.2%of homes in mapped high-risk flood zones are insured
$1.4 millionpaid on 61 flood claims since 1978
1993costliest year, with $768,970 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 Mercer County

$146,700median home value (Illinois $263,300, US $332,700)
1962median year homes were built (Illinois 1971, US 1980)
77%of homes built before 1980, before many modern wind, quake and flood building rules
2.9%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; 7,285 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
Rock Island CountyModerate13
Knox CountyLow9
Henry CountyLow14
Des Moines County, IALow25
Warren CountyVery Low7
Louisa County, IAVery Low18
Henderson CountyVery Low14

Common questions about Mercer County

What is the biggest natural hazard in Mercer County?

Inland flooding has the highest expected yearly losses in Mercer County, about $2 million a year in FEMA's estimate. Strong wind is second at $1.2 million.

How many federal disasters has Mercer County had?

Mercer County has been included in 13 federal disaster or emergency declarations for natural events since 1965, including 10 major disasters. The most recent was Severe Storms and Flooding in September 2019.

Is Mercer County a high-risk place to live?

Its overall rating is Very Low, 97th 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 Mercer County?

Standard home insurance does not cover flooding. About 1 in 500 homes in Mercer 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 Mercer County had?

NOAA records list 45 tornadoes in Mercer County since 1950. The strongest was an F3 tornado on August 15, 1978. The weather service has also logged 96 hail reports and 48 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.