Sully County, South Dakota
Natural disaster risk, federal disaster history and flood insurance facts.
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
- 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.
- Insulate pipes in outside walls, crawl spaces and garages.
- Know how to shut off the main water valve.
- Clear dry plants and debris within 5 feet of the house.
- Get home insurance quotes early; availability varies by area.
All 18 hazards
What the ratings mean ›| Hazard | Rating | Score | Expected loss a year | |
|---|---|---|---|---|
| Inland flooding | 14.1 | $3M | ||
| Cold wave | 51.1 | $2M | ||
| Wildfire | 70.6 | $270K | ||
| Hail | 34.7 | $217K | ||
| Tornado | 14.6 | $201K | ||
| Drought | 44.9 | $150K | ||
| Strong wind | 8.9 | $97K | ||
| Winter weather | 50.1 | $96K | ||
| Ice storm | 24.2 | $34K | ||
| Heat wave | 7.5 | $17K | ||
| Lightning | 2.0 | $10K | ||
| Earthquake | 6.8 | $10K | ||
| Landslide | 7.0 | $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
Most recent
Show all 14
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.
Strongest tornadoes
| Date | Strength | Near | Hurt / killed |
|---|---|---|---|
| Oct 1, 1971 | F2 | – | 0 / 0 |
| Apr 27, 1974 | F1 | – | 1 / 0 |
| Jul 16, 1982 | F1 | – | 0 / 0 |
| May 8, 1965 | F1 | – | 0 / 0 |
| Aug 24, 2006 | F1 | Onida | 0 / 0 |
Most damaging storms
| Date | Type | Near | Damage |
|---|---|---|---|
| Jun 1, 2019 | Flood | Laurel | $7M |
| Sep 2, 1999 | Flash Flood | Onida | $275K |
| Apr 1, 2019 | Flood | Laurel | $181K |
| Oct 1, 1971 | Tornado | – | $25K |
| Apr 27, 1974 | Tornado | – | $25K |
| Jul 16, 1982 | Tornado | – | $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 ›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
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 counties | Overall risk | Top hazard |
|---|---|---|
| Minnehaha County | Tornado | |
| Pennington County | Inland flooding | |
| Lincoln County | Tornado | |
| Brown County | Cold wave | |
| Brookings County | Inland flooding | |
| Meade County | Inland flooding | |
| Codington County | Inland flooding | |
| Lawrence County | Inland flooding |
Neighboring counties
| County | Overall risk | Declarations |
|---|---|---|
| Hughes County | 15 | |
| Dewey County | 14 | |
| Stanley County | 13 | |
| Potter County | 14 | |
| Hyde County | 13 |
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.