Fall River County, South Dakota Natural Disaster Risk
FEMA National Risk Index assessment · SD
Very LowComposite Risk Score
National percentile: 31th
Fall River County faces very low composite natural disaster risk (NRI Risk Index score 30.9, 31th national percentile), driven primarily by wildfire and winter weather exposure. Expected annual loss across all 18 hazard types is $7M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Fall River County carries a very low composite natural disaster risk, with a National Risk Index score of 30.9 out of 100 — placing it in the 31st 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.
Risk here concentrates in wildfire (uncontrolled fires that spread across wildland and into communities) at Medium risk — $2M in expected annual loss and about 0.01 events per year; winter weather (heavy snow, blizzards, and hazardous winter conditions) at Medium risk — $92K in expected annual loss and about 13.37 events per year; and hail (ice stones from severe thunderstorms that damage property and crops) at Low risk — $257K in expected annual loss and about 5.29 events per year. Across all hazards, FEMA estimates $7M in expected annual loss for a population of 7K.
Beyond physical exposure, Fall River County has a very high social vulnerability rating (how susceptible the population is to harm) and a high community resilience rating (its capacity to prepare for and recover from disasters). Higher vulnerability is partly offset by strong community resilience and recovery capacity.
History supports the rating: Fall River County has received 16 federal disaster declarations since 1997, including 6 for severe storm events and 3 for flood events. The most recent was Straight-Line Winds (straight-line winds), declared in April 2026.
Among 66 South Dakota counties, Fall River County ranks #25 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Wildfire | Medium | 0.01 / yr | $2M |
| Winter Weather | Medium | 13.37 / yr | $92K |
| Hail | Low | 5.29 / yr | $257K |
| Landslide | Very Low | 0.76 / yr | $2K |
| Lightning | Low | 43.64 / yr | $125K |
| Cold Wave | Low | 4.28 / yr | $480K |
| Riverine Flood | Low | 0.96 / yr | $3M |
| Earthquake | Very Low | 0.00 / yr | $75K |
| Strong Wind | Low | 1.91 / yr | $197K |
| Tornado | Low | 0.45 / yr | $336K |
| Drought | Very Low | 73.54 / yr | $13K |
| Heat Wave | Very Low | 0.96 / yr | $20K |
| Ice Storm | Very Low | 0.02 / yr | $5K |
| Avalanche | Very Low | 0.01 / yr | $1 |
| 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
Fall River County has received 16 federal disaster declarations since 1997, most recently Straight-Line Winds in April 2026. Most frequent causes: Severe Storm (6), Flood (3), Fire (3).
| Declared | Type | Disaster |
|---|---|---|
| April 2026 | Straight-Line Winds | Straight-Line Winds |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| September 2019 | Flood | Severe Storms and Flooding |
| June 2019 | Flood | Severe Winter Storm, Snowstorm, and Flooding |
| August 2018 | Fire | Vineyard Fire |
| February 2017 | Severe Storm | Severe Winter Storm |
| July 2015 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| November 2013 | Severe Storm | Severe Winter Storm, Snowstorm, and Flooding |
| September 2010 | Severe Storm | Severe Storms and Flooding |
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 Fall River County?
Fall River County has a composite FEMA National Risk Index score of 30.9 out of 100, placing it in the Very Low category and the 31th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Fall River County?
The three highest-rated hazards are Wildfire (Medium, $2M EAL), Winter Weather (Medium, $92K EAL), Hail (Low, $257K EAL). These account for most of the county's expected annual losses.
How does Fall River County compare to other South Dakota counties?
Fall River County ranks #25 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Fall River County had?
FEMA records 16 federal disaster declarations for Fall River County since 1997, most often 6 for severe storm events and 3 for flood events. The most recent was Straight-Line Winds, declared in April 2026.
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. Fall River County's $7M EAL is a statistical average, not a guarantee for any specific year or address.