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Cass County, Iowa

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

Relatively Low overall risk
17th of 99highest risk in Iowa
$17Mexpected losses a year
17federal declarations
1 in 333homes with flood insurance
Photo: Bold Frontiers, CC BY 2.0

Cass County, Iowa has a relatively low overall risk from natural hazards in FEMA's National Risk Index. Its risk score is higher than 60% of US counties. It ranks 17th of 99 counties in Iowa. The costliest hazards here are cold waves, inland flooding and drought. FEMA estimates about $17 million a year in expected losses, or roughly $1,264 per resident. Since 1965 it has been included in 17 federal disaster or emergency declarations for natural events (15 major disasters). The most recent was in February 2022 (severe storms, straight-line winds and tornadoes). Only 19 homes here carry federal flood insurance. Since 1978, federal flood insurance has paid about $335,000 on 57 claims here.

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

Top risks in Cass County

Cold wave

Moderate
$4.3 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.
$4.2 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.
$3.3 million a yearExpected losses. Damaging events about 9 times a year.
  • Check local water restrictions.
  • Choose drought-tolerant plants.
HazardRatingScoreExpected loss a year
Cold waveModerate86.9
$4M
Inland floodingLow43.4
$4M
DroughtHigh97.6
$3M
TornadoModerate75.8
$3M
Heat waveLow71.8
$775K
HailModerate79.5
$662K
Strong windModerate60.9
$584K
Ice stormLow56.4
$88K
Winter weatherLow48.2
$47K
LightningVery Low17.6
$47K
WildfireVery Low40.6
$21K
EarthquakeVery Low16.2
$15K
HurricaneVery Low17.6
$4K
LandslideLow65.5
$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 relatively high 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 Cass County. 2020s bar runs to November 2026.

By type

Flood7
Severe Storm6
Snowstorm2
Severe Ice Storm1
Hurricane1

Most recent

Feb 23, 2022Severe Storms, Straight-Line Winds, and TornadoesMajor disaster
Mar 23, 2019Severe Storms and FloodingMajor disaster
Mar 2, 2010Severe Winter StormMajor disaster
Feb 25, 2010Severe Winter Storms and SnowstormMajor disaster
May 27, 2008Severe Storms, Tornadoes, and FloodingMajor disaster
May 25, 2007Severe Storms, Flooding, and TornadoesMajor disaster
Mar 30, 2007SnowEmergency
Sep 10, 2005Hurricane Katrina EvacuationEmergency
May 25, 2004Severe Storms, Tornadoes, and FloodingMajor disaster
Jul 2, 1998Severe Storms, Tornadoes and FloodingMajor disaster
Show all 17
Nov 20, 1997Severe SnowstormsMajor disaster
Jul 9, 1993Severe Storms & FloodingMajor disaster
Dec 26, 1991Ice StormMajor disaster
Jul 12, 1991Severe Storms & FloodingMajor disaster
Jun 24, 1974Severe Storms & FloodingMajor disaster
Sep 26, 1972Severe Storms & FloodingMajor disaster
Apr 22, 1965FloodingMajor disaster

Iowa also had 11 statewide declarations that did not name single counties.

Storm history since 1956

Tornado risk by county ›

The National Weather Service has logged 546 storm reports in Cass County since 1956, with 0 deaths and 11 injuries and about $40 million in reported damage. The strongest on record here was an F3 tornado on April 8, 1999 near Massena.

40tornadoes
174hail reports, largest 3 inches
203damaging thunderstorm winds
44floods and flash floods

Strongest tornadoes

DateStrengthNearHurt / killed
Apr 8, 1999F3Massena0 / 0
Apr 20, 1964F3–1 / 0
Jun 7, 1984F2–8 / 0
May 6, 2007EF2Griswold0 / 0
Dec 15, 2021EF2Lewis0 / 0

Most damaging storms

DateTypeNearDamage
Jun 12, 2010FloodMarne$20M
Jun 14, 1998Flash FloodAtlantic$3M
Jun 7, 1984Tornado–$3M
Jun 21, 1997Thunderstorm WindCumberland$1M
May 6, 2007FloodAnita$1M
May 6, 2007TornadoGriswold$1M

Source: NOAA Storm Events Database, county-based reports through Jul 7, 2025. 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 Cass County

Check your address flood zone ›
0.3%of homes have federal flood insurance (19 policies)
20%of homes in mapped high-risk flood zones are insured
$335,414paid on 57 flood claims since 1978
2007costliest year, with $156,988 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 Cass County

$150,300median home value (Iowa $208,000, US $332,700)
1956median year homes were built (Iowa 1972, US 1980)
79%of homes built before 1980, before many modern wind, quake and flood building rules
2.3%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; 6,393 housing units.

Compare in Iowa

All 99 ›
Largest countiesOverall riskTop hazard
Polk CountyModerateInland flooding
Linn CountyModerateInland flooding
Scott CountyModerateInland flooding
Johnson CountyModerateTornado
Black Hawk CountyLowInland flooding
Woodbury CountyModerateInland flooding
Dallas CountyLowInland flooding
Dubuque CountyLowInland flooding

Neighboring counties

CountyOverall riskDeclarations
Pottawattamie CountyLow24
Shelby CountyVery Low18
Guthrie CountyVery Low15
Montgomery CountyVery Low18
Adair CountyLow15
Audubon CountyVery Low20
Adams CountyVery Low15

Common questions about Cass County

What is the biggest natural hazard in Cass County?

Cold wave has the highest expected yearly losses in Cass County, about $4.3 million a year in FEMA's estimate. Inland flooding is second at $4.2 million.

How many federal disasters has Cass County had?

Cass County has been included in 17 federal disaster or emergency declarations for natural events since 1965, including 15 major disasters. The most recent was Severe Storms, Straight-Line Winds, and Tornadoes in February 2022.

Is Cass County a high-risk place to live?

Its overall rating is Relatively Low, 17th highest of 99 in Iowa. 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 Cass County?

Standard home insurance does not cover flooding. About 1 in 333 homes in Cass 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 Cass County had?

NOAA records list 40 tornadoes in Cass County since 1950. The strongest was an F3 tornado on April 8, 1999 near Massena. The weather service has also logged 174 hail reports and 44 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.