Walworth County, SD: Tornado Risk and Shelter Cost
Walworth County, SD: what NOAA's tornado record says
NOAA's Storm Prediction Center has recorded 30 tornado tracks touching Walworth County since 1955 - about one every 2.5 years on average. That puts it in our Elevated band nationally. Against the rest of the country, that is the 68th percentile for frequency. Among 66 South Dakota counties in this dataset, Walworth County ranks 29 for how often a tornado touches down.
Has Walworth County ever had a violent tornado?
Yes, 1 time: Walworth County has an EF4-5 tornado on record. Wherever that history exists, FEMA's safe-room case applies regardless of how often the county gets touched overall.
Paying for it, if Walworth County's history says you should
A storm shelter or in-residence safe room typically runs $2,890-$13,280 nationally, around $7,645 for a common single-family installation. No state-administered rebate program specific to South Dakota was confirmed for this site - FEMA's own Hazard Mitigation Assistance grants fund 75% of an approved safe room nationwide, but only some states currently run a homeowner-facing application on top of that.
The gap a shelter does not cover
5,270 people live in Walworth County, and a tornado outbreak's power loss usually reaches far more of South Dakota than the tracks themselves touch. A portable battery unit is the faster, no-fuel way to bridge that outage.
County-level, not address-level
Treat this as a county-wide figure, not a prediction for one address. Walworth County covers about 707 square miles, so a single touch here counts the same as a single touch in a county a fraction of that size. And records from before the 1990s, NOAA notes, undercount weaker tornadoes in areas with less storm-spotting coverage at the time. Walworth County has about 5,270 residents.