Walworth County
South Dakota — Natural Disaster Risk Assessment
Very LowComposite Risk Score
National percentile: 40th
Walworth County faces very low composite natural disaster risk (NRI Risk Index score 39.5, 40th national percentile), driven primarily by cold wave and winter weather exposure. Expected annual loss across all 18 hazard types is $10M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Cold Wave | Medium | 11.16 / yr | $5M |
| Winter Weather | Medium | 17.95 / yr | $196K |
| Wildfire | Low | 0.00 / yr | $361K |
| Hail | Low | 3.23 / yr | $356K |
| Drought | Low | 20.95 / yr | $66K |
| Riverine Flood | Very Low | 0.61 / yr | $3M |
| Tornado | Low | 0.23 / yr | $367K |
| Ice Storm | Very Low | 0.57 / yr | $22K |
| Strong Wind | Low | 2.18 / yr | $134K |
| Heat Wave | Very Low | 2.74 / yr | $44K |
| Lightning | Very Low | 31.71 / yr | $31K |
| Earthquake | Very Low | 0.00 / yr | $6K |
| Landslide | Very Low | 0.11 / yr | $5 |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Walworth County?
Walworth County has a composite FEMA National Risk Index score of 39.5 out of 100, placing it in the Very Low category and the 40th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Walworth County?
The three highest-rated hazards are Cold Wave (Medium, $5M EAL), Winter Weather (Medium, $196K EAL), Wildfire (Low, $361K EAL). These account for most of the county's expected annual losses.
How does Walworth County compare to other South Dakota counties?
Walworth County ranks #17 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Walworth County's $10M EAL is a statistical average, not a guarantee for any specific year or address.