Brown County
South Dakota — Natural Disaster Risk Assessment
LowComposite Risk Score
National percentile: 74th
Brown County faces low composite natural disaster risk (NRI Risk Index score 73.5, 74th national percentile), driven primarily by winter weather and cold wave exposure. Expected annual loss across all 18 hazard types is $37M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Winter Weather | Very High | 20.11 / yr | $2M |
| Cold Wave | High | 13.37 / yr | $16M |
| Hail | Medium | 3.88 / yr | $2M |
| Strong Wind | Medium | 2.61 / yr | $2M |
| Ice Storm | Medium | 0.37 / yr | $534K |
| Wildfire | Low | 0.00 / yr | $353K |
| Tornado | Medium | 0.80 / yr | $3M |
| Riverine Flood | Low | 5.18 / yr | $11M |
| Heat Wave | Low | 3.63 / yr | $402K |
| Landslide | Very Low | 0.16 / yr | $1K |
| Drought | Very Low | 2.45 / yr | $31K |
| Earthquake | Very Low | 0.00 / yr | $68K |
| Lightning | Very Low | 31.78 / yr | $27K |
| 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 Brown County?
Brown County has a composite FEMA National Risk Index score of 73.5 out of 100, placing it in the Low category and the 74th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Brown County?
The three highest-rated hazards are Winter Weather (Very High, $2M EAL), Cold Wave (High, $16M EAL), Hail (Medium, $2M EAL). These account for most of the county's expected annual losses.
How does Brown County compare to other South Dakota counties?
Brown County ranks #4 of 66 South Dakota counties for overall natural disaster risk, with a 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. Brown County's $37M EAL is a statistical average, not a guarantee for any specific year or address.