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Jefferson County, Wisconsin

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

Relatively Low overall risk
18th of 72highest risk in Wisconsin
$42Mexpected losses a year
12federal declarations
1 in 200homes with flood insurance
Photo: U.S. Geological Survey, public domain

Jefferson County, Wisconsin has a relatively low overall risk from natural hazards in FEMA's National Risk Index. Its risk score is higher than 76% of US counties. It ranks 18th of 72 counties in Wisconsin. The costliest hazards here are inland flooding, tornadoes and cold waves. FEMA estimates about $42 million a year in expected losses, or roughly $493 per resident. Since 1965 it has been included in 12 federal disaster or emergency declarations for natural events (9 major disasters). The most recent was in June 2026 (severe storms, tornadoes and flooding). Fewer than 1 in 100 homes here carry federal flood insurance (153 policies). Since 1978, federal flood insurance has paid about $11 million on 503 claims here, including $9.0 million for floods in 2008.

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

Top risks in Jefferson County

$22.7 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.

Tornado

Moderate
$6.7 million a yearExpected losses. Damaging events about once every 2 years.
  • Pick a shelter spot: a basement, or an inside room on the lowest floor with no windows.
  • Turn on emergency alerts on your phone and keep a weather radio.

Cold wave

Moderate
$6.1 million a yearExpected losses. Damaging events about 5 times a year.
  • Insulate pipes in outside walls, crawl spaces and garages.
  • Know how to shut off the main water valve.
HazardRatingScoreExpected loss a year
Inland floodingModerate79.5
$23M
TornadoModerate86.1
$7M
Cold waveModerate85.3
$6M
HailModerate93.4
$3M
Heat waveLow71.3
$1M
Strong windModerate67.0
$1M
LightningModerate80.8
$896K
EarthquakeVery Low43.4
$225K
Winter weatherLow58.9
$104K
Ice stormLow43.9
$76K
DroughtLow37.6
$64K
WildfireVery Low39.9
$31K
HurricaneVery Low14.4
$4K
LandslideVery Low58.1
$3K

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 Jefferson County. 2020s bar runs to November 2026.

By type

Severe Storm5
Flood3
Tornado1
Drought1
Hurricane1
Snowstorm1

Most recent

Jun 30, 2026Severe Storms, Tornadoes, and FloodingMajor disaster
Jun 14, 2008Severe Storms, Tornadoes, and FloodingMajor disaster
Mar 19, 2008Record Snow and Near Record SnowEmergency
Aug 26, 2007Severe Storms and FloodingMajor disaster
Sep 13, 2005Hurricane Katrina EvacuationEmergency
Jun 18, 2004Severe Storms and FloodingMajor disaster
Jul 2, 1993Severe Storms, Tornadoes & FloodingMajor disaster
Aug 6, 1991Severe Storms & HailMajor disaster
Jun 17, 1976DroughtEmergency
Mar 23, 1976Severe Storms, Icing, Wind & FloodingMajor disaster
Show all 12
Apr 27, 1973Severe Storms & FloodingMajor disaster
Apr 21, 1965Tornadoes, Severe Storms & FloodingMajor disaster

Wisconsin also had 8 statewide declarations that did not name single counties.

Storm history since 1956

Tornado risk by county ›

The National Weather Service has logged 622 storm reports in Jefferson County since 1956, with 4 deaths and 53 injuries and about $172 million in reported damage. The strongest on record here was an F3 tornado on June 5, 1980.

51tornadoes
177hail reports, largest 4.25 inches
305damaging thunderstorm winds
53floods and flash floods

Strongest tornadoes

DateStrengthNearHurt / killed
Jun 5, 1980F3–0 / 0
Apr 11, 1965F2–28 / 3
Sep 28, 1986F2–1 / 0
Mar 27, 1991F2–0 / 0
Jun 15, 1981F2–3 / 0

Most damaging storms

DateTypeNearDamage
Jun 8, 2008Flash FloodLake Mills$137M
Apr 13, 2006HailLake Mills$4M
Apr 13, 2006HailJohnson Creek$4M
Apr 13, 2006HailConcord$4M
May 31, 1998Thunderstorm WindCountywide$3M
Apr 11, 1965Tornado–$3M

Source: NOAA Storm Events Database, county-based reports through Jul 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 Jefferson County

Check your address flood zone ›
0.5%of homes have federal flood insurance (153 policies)
16.7%of homes in mapped high-risk flood zones are insured
$11 millionpaid on 503 flood claims since 1978
2008costliest year, with $9 million 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 Jefferson County

$274,100median home value (Wisconsin $266,500, US $332,700)
1973median year homes were built (Wisconsin 1975, US 1980)
59%of homes built before 1980, before many modern wind, quake and flood building rules
3.6%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; 36,890 housing units.

Compare in Wisconsin

All 72 ›
Largest countiesOverall riskTop hazard
Milwaukee CountyHighCold wave
Dane CountyModerateInland flooding
Waukesha CountyModerateInland flooding
Brown CountyModerateInland flooding
Racine CountyModerateInland flooding
Outagamie CountyLowInland flooding
Winnebago CountyModerateInland flooding
Kenosha CountyModerateCold wave

Neighboring counties

CountyOverall riskDeclarations
Dane CountyModerate17
Waukesha CountyModerate17
Rock CountyModerate14
Walworth CountyLow11
Dodge CountyLow11

Common questions about Jefferson County

What is the biggest natural hazard in Jefferson County?

Inland flooding has the highest expected yearly losses in Jefferson County, about $22.7 million a year in FEMA's estimate. Tornado is second at $6.7 million.

How many federal disasters has Jefferson County had?

Jefferson County has been included in 12 federal disaster or emergency declarations for natural events since 1965, including 9 major disasters. The most recent was Severe Storms, Tornadoes, and Flooding in June 2026.

Is Jefferson County a high-risk place to live?

Its overall rating is Relatively Low, 18th highest of 72 in Wisconsin. 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 Jefferson County?

Standard home insurance does not cover flooding. About 1 in 200 homes in Jefferson 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 Jefferson County had?

NOAA records list 51 tornadoes in Jefferson County since 1950. The strongest was an F3 tornado on June 5, 1980. The weather service has also logged 177 hail reports and 53 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.