Bon Homme County, South Dakota Natural Disaster Risk
FEMA National Risk Index assessment · SD
Very LowComposite Risk Score
National percentile: 11th
Bon Homme County faces very low composite natural disaster risk (NRI Risk Index score 10.8, 11th national percentile), driven primarily by drought and ice storm exposure. Expected annual loss across all 18 hazard types is $7M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Bon Homme County at very low composite risk, with a National Risk Index score of 10.8 out of 100 — placing it in the 11th national percentile and among the lowest-risk counties in the country. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Bon Homme County's expected losses come from drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $2M in expected annual loss and about 24.75 events per year; ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Medium risk — $215K in expected annual loss and about 0.82 events per year; and winter weather (heavy snow, blizzards, and hazardous winter conditions) at Low risk — $128K in expected annual loss and about 14.89 events per year. Across all hazards, FEMA estimates $7M in expected annual loss for a population of 7K.
Beyond physical exposure, Bon Homme County has a very low social vulnerability rating (how susceptible the population is to harm) and a medium community resilience rating (its capacity to prepare for and recover from disasters). Both measures sit toward the lower end, indicating relatively modest population sensitivity.
The federal record bears this out: Bon Homme County has received 16 federal disaster declarations since 1976, including 6 for severe storm events and 5 for flood events. The most recent was Severe Storms, Straight-Line Winds, and Flooding (flood), declared in August 2024.
Among 66 South Dakota counties, Bon Homme County ranks #43 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | Medium | 24.75 / yr | $2M |
| Ice Storm | Medium | 0.82 / yr | $215K |
| Winter Weather | Low | 14.89 / yr | $128K |
| Wildfire | Very Low | 0.00 / yr | $83K |
| Hail | Low | 5.70 / yr | $410K |
| Cold Wave | Low | 6.21 / yr | $1M |
| Landslide | Very Low | 0.08 / yr | $685 |
| Tornado | Low | 0.39 / yr | $881K |
| Strong Wind | Low | 3.04 / yr | $338K |
| Heat Wave | Very Low | 6.47 / yr | $119K |
| Earthquake | Very Low | 0.00 / yr | $20K |
| Lightning | Very Low | 38.57 / yr | $67K |
| Riverine Flood | Very Low | 2.43 / yr | $2M |
| 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 |
Disaster History
Bon Homme County has received 16 federal disaster declarations since 1976, most recently Severe Storms, Straight-Line Winds, and Flooding in August 2024. Most frequent causes: Severe Storm (6), Flood (5), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| August 2024 | Flood | Severe Storms, Straight-Line Winds, and Flooding |
| June 2022 | Severe Storm | Severe Storm, Straight-Line Winds, Tornadoes, and Flooding |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| June 2019 | Flood | Severe Winter Storm, Snowstorm, and Flooding |
| July 2008 | Severe Storm | Severe Storms and Flooding |
| May 2007 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| December 2005 | Severe Storm | Severe Winter Storm |
| September 2005 | Coastal Storm | Hurricane Katrina Evacuation |
| April 1997 | Flood | Severe Flooding, Sever Winter Storms,Heavy Rains High Winds |
Showing the 10 most recent of 16 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Bon Homme County?
Bon Homme County has a composite FEMA National Risk Index score of 10.8 out of 100, placing it in the Very Low category and the 11th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Bon Homme County?
The three highest-rated hazards are Drought (Medium, $2M EAL), Ice Storm (Medium, $215K EAL), Winter Weather (Low, $128K EAL). These account for most of the county's expected annual losses.
How does Bon Homme County compare to other South Dakota counties?
Bon Homme County ranks #43 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Bon Homme County had?
FEMA records 16 federal disaster declarations for Bon Homme County since 1976, most often 6 for severe storm events and 5 for flood events. The most recent was Severe Storms, Straight-Line Winds, and Flooding, declared in August 2024.
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. Bon Homme County's $7M EAL is a statistical average, not a guarantee for any specific year or address.