Roberts County, South Dakota Natural Disaster Risk
FEMA National Risk Index assessment · SD
Very LowComposite Risk Score
National percentile: 38th
Roberts County faces very low composite natural disaster risk (NRI Risk Index score 37.8, 38th national percentile), driven primarily by winter weather and cold wave exposure. Expected annual loss across all 18 hazard types is $9M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Roberts County is very low, with a National Risk Index score of 37.8 out of 100 — placing it in the 38th 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 winter weather (heavy snow, blizzards, and hazardous winter conditions) at High risk — $257K in expected annual loss and about 22.95 events per year; cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $3M in expected annual loss and about 14.37 events per year; and ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Medium risk — $253K in expected annual loss and about 0.53 events per year. Across all hazards, FEMA estimates $9M in expected annual loss for a population of 10K.
Beyond physical exposure, Roberts County has a high social vulnerability rating (how susceptible the population is to harm) and a low community resilience rating (its capacity to prepare for and recover from disasters). That combination — a more vulnerable population with limited resilience — can amplify the human cost of any given event.
History supports the rating: Roberts County has received 24 federal disaster declarations since 1976, including 9 for flood events and 9 for severe storm events. The most recent was Flooding (flood), declared in July 2023.
Among 66 South Dakota counties, Roberts County ranks #20 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Winter Weather | High | 22.95 / yr | $257K |
| Cold Wave | Medium | 14.37 / yr | $3M |
| Ice Storm | Medium | 0.53 / yr | $253K |
| Wildfire | Low | 0.00 / yr | $174K |
| Hail | Low | 3.80 / yr | $372K |
| Landslide | Very Low | 0.16 / yr | $2K |
| Strong Wind | Medium | 2.68 / yr | $499K |
| Tornado | Low | 0.70 / yr | $920K |
| Riverine Flood | Low | 1.32 / yr | $3M |
| Heat Wave | Very Low | 2.58 / yr | $146K |
| Earthquake | Very Low | 0.00 / yr | $6K |
| Lightning | Very Low | 32.82 / yr | $21K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Drought | 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
Roberts County has received 24 federal disaster declarations since 1976, most recently Flooding in July 2023. Most frequent causes: Flood (9), Severe Storm (9), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| July 2023 | Flood | Flooding |
| February 2023 | Winter Storm | Severe Winter Storms and Snowstorm |
| 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 |
| May 2011 | Flood | Flooding |
| May 2010 | Flood | Flooding |
| March 2010 | Severe Storm | Severe Winter Storm |
Showing the 10 most recent of 24 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Roberts County?
Roberts County has a composite FEMA National Risk Index score of 37.8 out of 100, placing it in the Very Low category and the 38th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Roberts County?
The three highest-rated hazards are Winter Weather (High, $257K EAL), Cold Wave (Medium, $3M EAL), Ice Storm (Medium, $253K EAL). These account for most of the county's expected annual losses.
How does Roberts County compare to other South Dakota counties?
Roberts County ranks #20 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Roberts County had?
FEMA records 24 federal disaster declarations for Roberts County since 1976, most often 9 for flood events and 9 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. Roberts County's $9M EAL is a statistical average, not a guarantee for any specific year or address.