Grant County, South Dakota Natural Disaster Risk
FEMA National Risk Index assessment · SD
Very LowComposite Risk Score
National percentile: 19th
Grant County faces very low composite natural disaster risk (NRI Risk Index score 18.9, 19th national percentile), driven primarily by cold wave and ice storm exposure. Expected annual loss across all 18 hazard types is $11M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Grant County at very low composite risk, with a National Risk Index score of 18.9 out of 100 — placing it in the 19th 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 cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $5M in expected annual loss and about 13.63 events per year; ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Medium risk — $230K in expected annual loss and about 0.57 events per year; and winter weather (heavy snow, blizzards, and hazardous winter conditions) at Low risk — $134K in expected annual loss and about 23.21 events per year. Across all hazards, FEMA estimates $11M in expected annual loss for a population of 8K.
Beyond physical exposure, Grant County has a very low 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). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
History supports the rating: Grant County has received 22 federal disaster declarations since 1969, including 9 for flood events and 8 for severe storm events. The most recent was Flooding (flood), declared in July 2023.
Among 66 South Dakota counties, Grant County ranks #34 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Cold Wave | Medium | 13.63 / yr | $5M |
| Ice Storm | Medium | 0.57 / yr | $230K |
| Winter Weather | Low | 23.21 / yr | $134K |
| Wildfire | Very Low | 0.00 / yr | $94K |
| Hail | Low | 3.92 / yr | $466K |
| Landslide | Very Low | 0.10 / yr | $771 |
| Drought | Low | 5.45 / yr | $64K |
| Tornado | Low | 0.43 / yr | $1M |
| Heat Wave | Very Low | 2.68 / yr | $217K |
| Strong Wind | Low | 2.75 / yr | $281K |
| Riverine Flood | Very Low | 1.04 / yr | $3M |
| Earthquake | Very Low | 0.00 / yr | $9K |
| Lightning | Very Low | 33.46 / yr | $14K |
| 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
Grant County has received 22 federal disaster declarations since 1969, most recently Flooding in July 2023. Most frequent causes: Flood (9), Severe Storm (8), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| July 2023 | Flood | 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 |
| February 2017 | Severe Storm | Severe Winter Storm |
| August 2013 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| May 2011 | Flood | Flooding |
| May 2010 | Flood | Flooding |
| March 2010 | Severe Storm | Severe Winter Storm |
Showing the 10 most recent of 22 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Grant County?
Grant County has a composite FEMA National Risk Index score of 18.9 out of 100, placing it in the Very Low category and the 19th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Grant County?
The three highest-rated hazards are Cold Wave (Medium, $5M EAL), Ice Storm (Medium, $230K EAL), Winter Weather (Low, $134K EAL). These account for most of the county's expected annual losses.
How does Grant County compare to other South Dakota counties?
Grant County ranks #34 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Grant County had?
FEMA records 22 federal disaster declarations for Grant County since 1969, most often 9 for flood events and 8 for severe storm events. The most recent was Flooding, declared in July 2023.
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. Grant County's $11M EAL is a statistical average, not a guarantee for any specific year or address.