Custer County, South Dakota Natural Disaster Risk
FEMA National Risk Index assessment · SD
Very LowComposite Risk Score
National percentile: 16th
Custer County faces very low composite natural disaster risk (NRI Risk Index score 16.3, 16th national percentile), driven primarily by wildfire and winter weather exposure. Expected annual loss across all 18 hazard types is $9M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Custer County at very low composite risk, with a National Risk Index score of 16.3 out of 100 — placing it in the 16th 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 — $4M in expected annual loss and about 0.01 events per year; winter weather (heavy snow, blizzards, and hazardous winter conditions) at Low risk — $127K in expected annual loss and about 15.06 events per year; and landslide (downhill movement of rock, soil, and debris on unstable slopes) at Very Low risk — $2K in expected annual loss and about 0.59 events per year. Across all hazards, FEMA estimates $9M in expected annual loss for a population of 8K.
Beyond physical exposure, Custer 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 county's disaster history tells the same story: Custer County has received 17 federal disaster declarations since 1972, including 6 for fire events and 4 for flood events. The most recent was Straight-Line Winds (straight-line winds), declared in April 2026.
Among 66 South Dakota counties, Custer County ranks #37 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Wildfire | Medium | 0.01 / yr | $4M |
| Winter Weather | Low | 15.06 / yr | $127K |
| Landslide | Very Low | 0.59 / yr | $2K |
| Hail | Low | 6.21 / yr | $292K |
| Earthquake | Very Low | 0.00 / yr | $63K |
| Lightning | Low | 45.32 / yr | $123K |
| Cold Wave | Very Low | 3.98 / yr | $399K |
| Tornado | Very Low | 0.37 / yr | $396K |
| Riverine Flood | Very Low | 1.18 / yr | $3M |
| Drought | Very Low | 62.71 / yr | $2K |
| Strong Wind | Very Low | 2.52 / yr | $185K |
| Heat Wave | Very Low | 0.38 / yr | $8K |
| Ice Storm | Very Low | 0.01 / yr | $2K |
| 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
Custer County has received 17 federal disaster declarations since 1972, most recently Straight-Line Winds in April 2026. Most frequent causes: Fire (6), Flood (4), Severe Storm (3).
| Declared | Type | Disaster |
|---|---|---|
| April 2026 | Straight-Line Winds | Straight-Line Winds |
| March 2026 | Fire | Qury Fire |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| September 2019 | Flood | Severe Storms and Flooding |
| December 2017 | Fire | Legion Lake Fire |
| November 2013 | Severe Storm | Severe Winter Storm, Snowstorm, and Flooding |
| July 2012 | Fire | Myrtle Fire |
| September 2005 | Coastal Storm | Hurricane Katrina Evacuation |
| August 2002 | Fire | Sd - Battle Creek Fire - 08/18/02 |
Showing the 10 most recent of 17 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Custer County?
Custer County has a composite FEMA National Risk Index score of 16.3 out of 100, placing it in the Very Low category and the 16th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Custer County?
The three highest-rated hazards are Wildfire (Medium, $4M EAL), Winter Weather (Low, $127K EAL), Landslide (Very Low, $2K EAL). These account for most of the county's expected annual losses.
How does Custer County compare to other South Dakota counties?
Custer County ranks #37 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Custer County had?
FEMA records 17 federal disaster declarations for Custer County since 1972, most often 6 for fire events and 4 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. Custer County's $9M EAL is a statistical average, not a guarantee for any specific year or address.