Union County, SD
FEMA National Risk Index scores, disaster declarations & hazard data
Union County has experienced 19 federally declared disasters since 1969, most recently Severe Storms, Straight-Line Winds, And Flooding in 2024. Its overall natural hazard risk is rated Very Low — among the lowest-risk counties in the country.
Union County's highest-rated hazards are wildfire, winter weather, and drought, with its top risk rated "Relatively Low" by FEMA's National Risk Index. Recorded storm events have decreased 50% over the past five years compared to the prior five-year period. Community vulnerability is relatively low (6th 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. Union 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 |
|---|---|---|
| 2024 | Flood | Severe Storms, Straight-Line Winds, And Flooding |
| 2020 | Severe Storm | Severe Storms, Tornadoes, And Flooding |
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2019 | Flood | Severe Winter Storm, Snowstorm, And Flooding |
| 2019 | Flood | Severe Storms And Flooding |
| 2014 | Flood | Severe Storms, Tornadoes, And Flooding |
| 2013 | Severe Storm | Severe Storms, Tornado, And Flooding |
| 2011 | Severe Storm | Severe Storms And Flooding |
| 2011 | Flood | Flooding |
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 | 77.6 | 0 | 0 | — |
| Inland Flooding | Relatively Low | 47.5 | 107 | 0 | $55.8M |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Very Low | 16.6 | — | — | — |
| Heat Wave | Very Low | 33.8 | 21 | 0 | — |
| Tornado | Relatively Moderate | 69.2 | 0 | 0 | — |
| Hurricane | Not Applicable | — | 0 | 0 | — |
| Hail | Relatively Moderate | 73.5 | 27 | 0 | — |
| Strong Wind | Relatively Low | 26 | 0 | 0 | — |
| Winter Weather | Relatively Moderate | 77.5 | 0 | 0 | — |
| Ice Storm | Relatively Moderate | 67.7 | — | — | — |
| Cold Wave | Relatively Low | 34.8 | — | — | — |
| Lightning | Relatively Low | 32.1 | 1 | 0 | $2.5M |
| Drought | Relatively Moderate | 74.6 | 0 | 0 | — |
| Landslide | Very Low | 35.8 | 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
Union County ranks in the 6th percentile (Very 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 | 6th | Very low |
| Socioeconomic status | 5th | Very low |
| Household characteristics | 37th | Low |
| Racial & ethnic minority status | 31st | Low |
| Housing type & transportation | 8th | Very low |
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 | 48th | Relatively Moderate |
| Risk to homes | 55th | Relatively Moderate |
| Buildings in direct exposure zone | 36.9% | — |
NOAA tracked 156 weather events in this county over 2016–2025: 104 in 2016–20 vs 52 in 2021–25 (-50% — 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 Union County?
According to the FEMA National Risk Index, the highest-risk hazards in Union County, South Dakota are wildfire, winter weather, and drought. The county's overall natural hazard risk is rated Very Low — among the lowest-risk counties in the country.
Has Union County received federal disaster declarations?
Yes. Union County has received 19 federal disaster declarations since 1969, including declarations in 2024. The most common disaster type on record is flood (9 declarations).
Has Union County had any FEMA disaster declarations in 2024, 2025, or 2026?
Yes. Recent federal disaster declarations for Union County include Severe Storms, Straight-Line Winds, And Flooding (2024). See the declarations table above for the full history since 1969.
How does Union County's natural hazard risk compare to nearby counties?
Among neighboring counties, Lincoln County, SD has the highest overall natural hazard risk (Relatively Low) and Dixon County, NE has the lowest (Very Low). Union County is rated Very Low overall.
How is Union County's composite disaster risk index calculated?
Union 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. Union County's composite score of 37 means its overall natural hazard risk is higher than 37% of US counties.