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Sully County, South Dakota

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

Very Low overall risk
56th of 66highest risk in South Dakota
$5Mexpected losses a year
14federal declarations
Photo: U.S. Geological Survey, public domain

Sully County, South Dakota has a very low overall risk from natural hazards in FEMA's National Risk Index. Its risk score is lower than 94% of US counties. It ranks 56th of 66 counties in South Dakota. The costliest hazards here are inland flooding, cold waves and wildfires. FEMA estimates about $5.2 million a year in expected losses, or roughly $3,606 per resident. Since 1976 it has been included in 14 federal disaster or emergency declarations for natural events (12 major disasters). The most recent was in June 2019 (severe winter storm, snowstorm and flooding). No 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 Sully County

$2.6 million a yearExpected losses. Damaging events about once every 2 years.
  • 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.
$1.5 million a yearExpected losses. Damaging events about 8 times a year.
  • Insulate pipes in outside walls, crawl spaces and garages.
  • Know how to shut off the main water valve.
$270,183 a yearExpected losses. Damaging events about once every 920 years.
  • Clear dry plants and debris within 5 feet of the house.
  • Get home insurance quotes early; availability varies by area.
HazardRatingScoreExpected loss a year
Inland floodingVery Low14.1
$3M
Cold waveLow51.1
$2M
WildfireLow70.6
$270K
HailLow34.7
$217K
TornadoVery Low14.6
$201K
DroughtLow44.9
$150K
Strong windVery Low8.9
$97K
Winter weatherLow50.1
$96K
Ice stormVery Low24.2
$34K
Heat waveVery Low7.5
$17K
LightningVery Low2.0
$10K
EarthquakeVery Low6.8
$10K
LandslideVery Low7.0
$21

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 relatively high in FEMA's measures.

Federal disaster history

Recent disasters nationwide ›

Declarations by decade

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

By type

Flood6
Severe Storm5
Drought1
Snowstorm1
Coastal Storm1

Most recent

Jun 7, 2019Severe Winter Storm, Snowstorm, and FloodingMajor disaster
Feb 1, 2017Severe Winter StormMajor disaster
May 13, 2011FloodingMajor disaster
May 13, 2010FloodingMajor disaster
Mar 10, 2010Severe Winter StormMajor disaster
Sep 10, 2005Hurricane Katrina EvacuationEmergency
Jul 22, 2005Severe StormMajor disaster
Apr 7, 1997Severe Flooding, Sever Winter Storms,Heavy Rains High WindsMajor disaster
Jan 10, 1997Severe Winter Storms and Blizzard ConditionsMajor disaster
May 26, 1995FloodingMajor disaster
Show all 14
Mar 14, 1995Severe Winter StormsMajor disaster
Jun 21, 1994Severe Storms and FloodingMajor disaster
May 3, 1986Severe Storms & FloodingMajor disaster
Jun 17, 1976DroughtEmergency

South Dakota also had 46 statewide declarations that did not name single counties.

Storm history since 1956

Tornado risk by county ›

The National Weather Service has logged 277 storm reports in Sully County since 1956, with 0 deaths and 1 injury and about $7.9 million in reported damage. The strongest on record here was an F2 tornado on October 1, 1971.

21tornadoes
146hail reports, largest 4.25 inches
99damaging thunderstorm winds
11floods and flash floods

Strongest tornadoes

DateStrengthNearHurt / killed
Oct 1, 1971F2–0 / 0
Apr 27, 1974F1–1 / 0
Jul 16, 1982F1–0 / 0
May 8, 1965F1–0 / 0
Aug 24, 2006F1Onida0 / 0

Most damaging storms

DateTypeNearDamage
Jun 1, 2019FloodLaurel$7M
Sep 2, 1999Flash FloodOnida$275K
Apr 1, 2019FloodLaurel$181K
Oct 1, 1971Tornado–$25K
Apr 27, 1974Tornado–$25K
Jul 16, 1982Tornado–$25K

Source: NOAA Storm Events Database, county-based reports through Jul 25, 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 Sully County

Check your address flood zone ›
0%of homes have federal flood insurance (0 policies)
0%of homes in mapped high-risk flood zones are insured
$22,793paid on 5 flood claims since 1978
1997costliest year, with $21,280 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 Sully County

$205,400median home value (South Dakota $257,400, US $332,700)
1979median year homes were built (South Dakota 1980, US 1980)
51%of homes built before 1980, before many modern wind, quake and flood building rules
16%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; 934 housing units.

Compare in South Dakota

All 66 ›
Largest countiesOverall riskTop hazard
Minnehaha CountyModerateTornado
Pennington CountyLowInland flooding
Lincoln CountyLowTornado
Brown CountyLowCold wave
Brookings CountyLowInland flooding
Meade CountyLowInland flooding
Codington CountyLowInland flooding
Lawrence CountyLowInland flooding

Neighboring counties

CountyOverall riskDeclarations
Hughes CountyVery Low15
Dewey CountyLow14
Stanley CountyVery Low13
Potter CountyVery Low14
Hyde CountyVery Low13

Common questions about Sully County

What is the biggest natural hazard in Sully County?

Inland flooding has the highest expected yearly losses in Sully County, about $2.6 million a year in FEMA's estimate. Cold wave is second at $1.5 million.

How many federal disasters has Sully County had?

Sully County has been included in 14 federal disaster or emergency declarations for natural events since 1976, including 12 major disasters. The most recent was Severe Winter Storm, Snowstorm, and Flooding in June 2019.

Is Sully County a high-risk place to live?

Its overall rating is Very Low, 56th highest of 66 in South Dakota. 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 Sully County?

Standard home insurance does not cover flooding. Lenders require it in mapped high-risk zones, but many flood claims come from outside those zones.

How many tornadoes has Sully County had?

NOAA records list 21 tornadoes in Sully County since 1950. The strongest was an F2 tornado on October 1, 1971. The weather service has also logged 146 hail reports and 11 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.