Brown County, SD
FEMA National Risk Index scores, disaster declarations & hazard data
Brown County has experienced 19 federally declared disasters since 1969, most recently Flooding in 2023. Its overall natural hazard risk is rated Relatively Low — lower risk than most US counties.
Brown County's highest-rated hazards are winter weather, cold wave, and hail, with its top risk rated "Very High" by FEMA's National Risk Index. Recorded storm events have increased 17% over the past five years compared to the prior five-year period. Community vulnerability is relatively low (27th percentile nationally), indicating stronger recovery capacity than most US counties.
Past disasters & FEMA designations
A federal disaster declaration officially designates a county for FEMA disaster assistance. Brown County has been designated in 19 declarations since 1969, covering 5 disaster types including flood (9), severe storm (6), biological (2).
| Year | Type | Event name |
|---|---|---|
| 2023 | Flood | Flooding |
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2019 | Flood | Severe Winter Storm, Snowstorm, And Flooding |
| 2011 | Flood | Flooding |
| 2010 | Flood | Flooding |
| 2009 | Severe Storm | Severe Storms And Flooding |
| 2007 | Severe Storm | Severe Storms, Tornadoes, And Flooding |
| 2006 | Severe Storm | Severe Winter Storm |
| 2005 | Coastal Storm | Hurricane Katrina Evacuation |
Showing the 10 most recent of 19 total declarations since 1969.
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 | 77.1 | 0 | 0 | — |
| Inland Flooding | Relatively Low | 63.1 | 79 | 0 | $895K |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Very Low | 27.8 | — | — | — |
| Heat Wave | Relatively Low | 48.7 | 9 | 0 | — |
| Tornado | Relatively Moderate | 70.1 | 6 | 0 | — |
| Hurricane | Not Applicable | — | 0 | 0 | — |
| Hail | Relatively Moderate | 86.5 | 84 | 0 | — |
| Strong Wind | Relatively Moderate | 82.5 | 0 | 0 | — |
| Winter Weather | Very High | 98.2 | 0 | 0 | — |
| Ice Storm | Relatively Moderate | 81.7 | — | — | — |
| Cold Wave | Relatively High | 96.4 | — | — | — |
| Lightning | Very Low | 7.6 | 0 | 0 | — |
| Drought | Very Low | 30.6 | 0 | 0 | — |
| Landslide | Very Low | 44.4 | 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
Brown County ranks in the 27th percentile (Low) 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 | 27th | Low |
| Socioeconomic status | 15th | Very low |
| Household characteristics | 26th | Low |
| Racial & ethnic minority status | 42nd | Low |
| Housing type & transportation | 59th | Moderate |
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 | 53rd | Relatively Moderate |
| Risk to homes | 55th | Relatively Moderate |
| Buildings in direct exposure zone | 47.5% | — |
NOAA tracked 178 weather events in this county over 2016–2025: 82 in 2016–20 vs 96 in 2021–25 (+17% — frequency increasing).
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 Brown County?
According to the FEMA National Risk Index, the highest-risk hazards in Brown County, South Dakota are winter weather, cold wave, and hail. The county's overall natural hazard risk is rated Relatively Low — lower risk than most US counties.
Has Brown County received federal disaster declarations?
Yes. Brown County has received 19 federal disaster declarations since 1969, including declarations in 2023. The most common disaster type on record is flood (9 declarations).
Has Brown County had any FEMA disaster declarations in 2024, 2025, or 2026?
No federal disaster declarations have been recorded for Brown County since the start of 2024. Its most recent declaration on record is Flooding in 2023.
How does Brown County's natural hazard risk compare to nearby counties?
Among neighboring counties, Day County, SD has the highest overall natural hazard risk (Very Low) and Edmunds County, SD has the lowest (Very Low). Brown County is rated Relatively Low overall.
How is Brown County's composite disaster risk index calculated?
Brown 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. Brown County's composite score of 74 means its overall natural hazard risk is higher than 74% of US counties.