Aurora County, South Dakota Natural Disaster Risk
FEMA National Risk Index assessment · SD
Very LowComposite Risk Score
National percentile: 20th
Aurora County faces very low composite natural disaster risk (NRI Risk Index score 19.6, 20th national percentile), driven primarily by ice storm and drought exposure. Expected annual loss across all 18 hazard types is $8M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Aurora County at very low composite risk, with a National Risk Index score of 19.6 out of 100 — placing it in the 20th 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.
The county's risk is driven primarily by ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Medium risk — $539K in expected annual loss and about 0.46 events per year; drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $902K in expected annual loss and about 18.29 events per year; and cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $3M in expected annual loss and about 7.00 events per year. Across all hazards, FEMA estimates $8M in expected annual loss for a population of 3K.
Beyond physical exposure, Aurora County has a 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.
The federal record bears this out: Aurora County has received 23 federal disaster declarations since 1976, including 9 for flood events and 8 for severe storm events. The most recent was Severe Storms, Straight-Line Winds, and Flooding (flood), declared in August 2024.
Among 66 South Dakota counties, Aurora County ranks #33 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Ice Storm | Medium | 0.46 / yr | $539K |
| Drought | Medium | 18.29 / yr | $902K |
| Cold Wave | Medium | 7.00 / yr | $3M |
| Wildfire | Low | 0.00 / yr | $139K |
| Winter Weather | Low | 16.11 / yr | $85K |
| Hail | Low | 4.67 / yr | $302K |
| Tornado | Low | 0.36 / yr | $663K |
| Earthquake | Very Low | 0.00 / yr | $25K |
| Strong Wind | Very Low | 2.90 / yr | $156K |
| Landslide | Very Low | 0.07 / yr | $64 |
| Riverine Flood | Very Low | 0.61 / yr | $2M |
| Heat Wave | Very Low | 6.05 / yr | $16K |
| Lightning | Very Low | 36.26 / yr | $9K |
| 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
Aurora County has received 23 federal disaster declarations since 1976, most recently Severe Storms, Straight-Line Winds, and Flooding in August 2024. Most frequent causes: Flood (9), Severe Storm (8), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| August 2024 | Flood | Severe Storms, Straight-Line Winds, and Flooding |
| June 2022 | Severe Storm | Severe Storm, Straight-Line Winds, Tornadoes, and Flooding |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| November 2019 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| September 2019 | Flood | Severe Storms and Flooding |
| June 2019 | Flood | Severe Winter Storm, Snowstorm, and Flooding |
| May 2011 | Flood | Flooding |
| May 2010 | Flood | Flooding |
| March 2010 | Severe Storm | Severe Winter Storm |
Showing the 10 most recent of 23 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Aurora County?
Aurora County has a composite FEMA National Risk Index score of 19.6 out of 100, placing it in the Very Low category and the 20th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Aurora County?
The three highest-rated hazards are Ice Storm (Medium, $539K EAL), Drought (Medium, $902K EAL), Cold Wave (Medium, $3M EAL). These account for most of the county's expected annual losses.
How does Aurora County compare to other South Dakota counties?
Aurora County ranks #33 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Aurora County had?
FEMA records 23 federal disaster declarations for Aurora County since 1976, most often 9 for flood events and 8 for severe storm events. The most recent was Severe Storms, Straight-Line Winds, and Flooding, declared in August 2024.
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. Aurora County's $8M EAL is a statistical average, not a guarantee for any specific year or address.