Dewey County, SD
FEMA National Risk Index scores, disaster declarations & hazard data
Dewey County has experienced 17 federally declared disasters since 1976, most recently Covid-19 in 2020. Its overall natural hazard risk is rated Relatively Low — lower risk than most US counties.
Dewey County's highest-rated hazards are cold wave, winter weather, and wildfire, with its top risk rated "Very High" by FEMA's National Risk Index. NOAA records 84 storm events in the county over the past decade. Community vulnerability is elevated (83rd percentile nationally), suggesting residents may face greater difficulty recovering from major disasters.
Past disasters & FEMA designations
A federal disaster declaration officially designates a county for FEMA disaster assistance. Dewey County has been designated in 17 declarations since 1976, covering 6 disaster types including severe storm (7), biological (3), flood (3).
| Year | Type | Event name |
|---|---|---|
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2019 | Flood | Severe Winter Storm, Snowstorm, And Flooding |
| 2017 | Severe Storm | Severe Winter Storm |
| 2014 | Severe Storm | Severe Winter Storm, Snowstorm, And Flooding |
| 2014 | Flood | Severe Storms, Tornadoes, And Flooding |
| 2010 | Severe Storm | Severe Winter Storm |
| 2010 | Severe Storm | Severe Storms, Tornadoes, And Flooding |
| 2009 | Snowstorm | Severe Winter Storm And Record And Near Record Snow |
Showing the 10 most recent of 17 total declarations since 1976.
Source: FEMA OpenFEMA Disaster Declarations Summaries. A single disaster can produce more than one record per county. Data current through September 2026.
Risk by hazard type
| Hazard | Risk rating | Risk score | Recorded events | Deaths | Prop. damage |
|---|---|---|---|---|---|
| Wildfire | Relatively Low | 83 | 0 | 0 | — |
| Inland Flooding | Very Low | 17.4 | 9 | 0 | $199K |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Very Low | 12.2 | — | — | — |
| Heat Wave | Very Low | 23.3 | 5 | 0 | — |
| Tornado | Very Low | 24.4 | 0 | 0 | — |
| Hurricane | Not Applicable | — | 0 | 0 | — |
| Hail | Relatively Low | 57.8 | 70 | 0 | — |
| Strong Wind | Relatively Low | 23 | 0 | 0 | — |
| Winter Weather | Relatively High | 85.3 | 0 | 0 | — |
| Ice Storm | Relatively Moderate | 65.2 | — | — | — |
| Cold Wave | Very High | 99 | — | — | — |
| Lightning | Very Low | 16.4 | 0 | 0 | — |
| Drought | Very Low | 28.1 | 0 | 0 | — |
| Landslide | Very Low | 31.9 | 0 | 0 | — |
| Avalanche | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic Activity | Not Applicable | — | — | — | — |
Scores are 0–100 percentiles relative to all US counties — higher means more exposed, not that a disaster is likely this year. Event counts: NOAA Storm Events 2016–2026; earthquake counts from USGS ComCat (M3.0+, 1996–2026). See the methodology page for details.
Community vulnerability
Dewey County ranks in the 83rd percentile (High) for community vulnerability — a measure of how hard disaster impacts tend to hit residents. Higher vulnerability means more displacement, worse health outcomes, and slower recovery after a disaster.
| SVI theme | Percentile | Vulnerability level |
|---|---|---|
| Overall | 83rd | High |
| Socioeconomic status | 89th | High |
| Household characteristics | 25th | Low |
| Racial & ethnic minority status | 98th | High |
| Housing type & transportation | 82nd | High |
Source: CDC/ATSDR Social Vulnerability Index 2022. Percentiles compare counties nationally — higher means more vulnerable relative to other counties. See CDC SVI for full methodology.
Future risk outlook
| Wildfire metric | National percentile | Level |
|---|---|---|
| Burn probability | 68th | Relatively High |
| Risk to homes | 70th | Relatively High |
| Buildings in direct exposure zone | 68.9% | — |
NOAA tracked 84 weather events in this county over 2016–2025: 45 in 2016–20 vs 39 in 2021–25 (-13% — frequency decreasing).
Wildfire: USDA Forest Service Wildfire Risk to Communities (RDS-2020-0016-2) — modeled values, not annual forecasts. See wildfirerisk.org. Inland flood and heat projections pending data availability; coastal sea-level projections are available for select coastal counties below — see the data page.
Nearby counties
Frequently asked questions
What natural hazards pose the greatest risk in Dewey County?
According to the FEMA National Risk Index, the highest-risk hazards in Dewey County, South Dakota are cold wave, winter weather, and wildfire. The county's overall natural hazard risk is rated Relatively Low — lower risk than most US counties.
Has Dewey County received federal disaster declarations?
Yes. Dewey County has received 17 federal disaster declarations since 1976, including declarations in 2020. The most common disaster type on record is severe storm (7 declarations).
Has Dewey County had any FEMA disaster declarations in 2024, 2025, or 2026?
No federal disaster declarations have been recorded for Dewey County since the start of 2024. Its most recent declaration on record is Covid-19 in 2020.
How does Dewey County's natural hazard risk compare to nearby counties?
Among neighboring counties, Walworth County, SD has the highest overall natural hazard risk (Very Low) and Stanley County, SD has the lowest (Very Low). Dewey County is rated Relatively Low overall.
How is Dewey County's composite disaster risk index calculated?
Dewey County's composite disaster risk index — officially FEMA's National Risk Index (NRI) — scores every US county on a 0–100 percentile scale across 18 natural hazard types, factoring in expected annual loss, social vulnerability, and community resilience. Dewey County's composite score of 79 means its overall natural hazard risk is higher than 79% of US counties.