Sully County, SD Environment & Hazard Risk
Very Low natural hazard risk, led by wildfire. 477 storm events since 1996.
- Expected yearly loss
- $5.2M
- Very Low nationally
- Storm events since 1996
- 477
- Most often hail
- Hurricanes nearby
- 0
- Since 1851
Natural hazard risk
FEMA National Risk Index, December 2025
Overall risk
Very Low
Score 6.3 of 100
Social vulnerability
Very Low
Score 10.6 of 100
Community resilience
Relatively High
Score 75.2 of 100
Community resilience runs the other way: a higher rating means a community can recover faster.
Building value exposed: $2B · Agriculture value exposed: $177M · Risk-adjusted yearly loss: $3.6M
Risk by hazard
- WildfireRelatively Low$270K/yr expected annual loss, about once every 918 years
- Cold waveRelatively Low$1.5M/yr expected annual loss, about 7.7 events a year
- Winter weatherRelatively Low$96.4K/yr expected annual loss, about 17 events a year
- DroughtRelatively Low$150K/yr expected annual loss, about 36 events a year
- HailRelatively Low$217K/yr expected annual loss, about 3.3 events a year
- Ice stormVery Low$34.4K/yr expected annual loss, about once every 2 years
- TornadoVery Low$201K/yr expected annual loss, about once every 3 years
- Strong windVery Low$97K/yr expected annual loss, about 2.5 events a year
- Heat waveVery Low$16.6K/yr expected annual loss, about 3.8 events a year
- LandslideVery Low$21/yr expected annual loss, about once every 8 years
- EarthquakeVery Low$9,785/yr expected annual loss, about once every 3,215 years
- LightningVery Low$9,943/yr expected annual loss, about 32 events a year
Bars show the national percentile score (0 to 100) for each hazard. Dollar figures are expected annual losses to buildings, people and crops. Not rated here: avalanche, coastal flooding, hurricane, riverine flooding, tsunami, volcanic activity.
Flood risk and insurance
National Flood Insurance Program and FEMA flood maps
Check the flood zone for an address
- Homes in high-risk flood zones
- 0
- Flood claims since 1978
- 5
- Claims paid since 1978
- $22.8K
Flood claims paid per year
- Flooding$21.3K · 4 claims
Storm history
Since 1996: 477 events, 0 deaths, $7.8M in damage
- Hail127
- Thunderstorm Wind81
- High Wind71
- Blizzard39
- Drought36
- Heavy Snow28
- Extreme Cold/Wind Chill28
- Winter Storm23
- Flood10
- Excessive Heat10
Events per year
21 tornadoes on record (EF0 1, F0 13, F1 4, F2 1).
Most damaging storms
Since 1996, ranked by deaths, injuries and damage
- Flood06/01/2019
Laurel, Sully County
$7.3M damage
What happened
Spring snowmelt and heavy rain flooding from March, April, and May continued into June. This combined with above normal June rainfall resulted in hundreds of thousands of acres of crops damaged or unplanted across central and northeast South Dakota. For the entire state of South Dakota, nearly 4 million acres of crops were left unplanted as a result of the flooding. Total damaged or unplanted crop loss estimates for central and northeast South Dakota were near 307 million dollars.
- Heavy Snow03/27/2008
Sully
1 injured
What happened
A 49-year old Lebanon South Dakota man received frostbite and hypothermia when he abandoned his stuck vehicle and walked into a barbed wire fence and became trapped. He was found southeast of Onida in the early morning hours and flown to a Sioux Falls hospital in critical condition. His body temperature was in the mid 80s when he was found.
- Flash Flood09/03/1999
Onida, Sully County
$275K damage
What happened
Very heavy rains from thunderstorms repeatedly going over the same area resulted in extensive flash flooding in a 30 to 40 mile wide band from Fort Pierre in southeast Stanley County to Hecla in northeast Brown County. Rainfall amounts in this corridor ranged from 3 to 7 inches. As a result, the communities of Blunt in Hughes County and Onida in Sully county were severely flooded. Most of the homes and businesses were flooded throughout Blunt and Onida causing severe damage. Only a few homes in these communities were spared from receiving water in there basements. Most homes also experienced sewer backup. The sewer systems in both Onida and Blunt were flooded and shutdown. Many people had to go to temporary shelters as a result of the flooding. Aberdeen and Fort Pierre had a lot of street flooding resulting in road closures and detours. Also, several basements in Aberdeen and Fort Pierre had sewer backup. The heavy rain flooded many township and county roads along with several state and U.S. highways. Sections of Highways 14, 20, 83, and 1806 along with many other roads in central and northeast South Dakota had to be closed. Many of the township and county roads...
- Flood04/01/2019
Laurel, Sully County
$181K damage
Drinking water
2 community water systems serve about 12,491 people. Violations since 2021.
None of the systems serving this county had a health-based violation in this period.
- Mid-Dakota Rural WaterServes 11,833 · Surface water · PrivateNo health violations
- OnidaServes 658 · Purchased surface water · Local governmentNo health violations
Largest systems by population served. Monitoring and reporting violations mean required tests or notices were late or missing, not that the water was unsafe.
Pollution sites
0 Superfund sites and 1 toxic release facility in Sully County
Superfund sites
None in this county.
Toxic release facilities
- Ring-Neck Energy & Feed LLC23,178 lbs released, Onida
Total: 23,178 lbs in 2024, 23,178 lbs to air.
Superfund sitesToxic release facilitiesEPA inspections and enforcementAir toxics cancer risk4 historic places
Frequently asked questions
- How risky is Sully County for natural disasters?
- FEMA rates Sully County very low for overall natural hazard risk, with expected losses of $5.2M a year. The highest-rated hazards are wildfire (relatively low), cold wave (relatively low), winter weather (relatively low).
- What storms are most common in Sully County?
- Since 1996, NOAA recorded 477 storm events affecting Sully County, most often hail (127), thunderstorm wind (81), high wind (71).
- How many tornadoes have hit Sully County?
- 21 tornadoes have been recorded in Sully County since 1950.
- What is the weather like in Sully County?
- At Onida 4 NW, average highs reach 87°F in Jul and lows fall to 7°F in Jan, with 21.1 inches of rain a year (1991-2020 normals).
Source: FEMA (National Risk Index, NFIP), NOAA (Storm Events, HURDAT2, Climate Normals), EPA · Last updated 08/01/2026 · Storm counts include events in forecast zones that touch the county. This product uses the FEMA OpenFEMA API, but is not endorsed by FEMA.