Tripp County, South Dakota Natural Disaster Risk
FEMA National Risk Index assessment · SD
Very LowComposite Risk Score
National percentile: 36th
Tripp County faces very low composite natural disaster risk (NRI Risk Index score 36.5, 36th national percentile), driven primarily by cold wave and winter weather 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 Tripp County at very low composite risk, with a National Risk Index score of 36.5 out of 100 — placing it in the 36th 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.
Most of Tripp County's expected losses come from cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $3M in expected annual loss and about 5.47 events per year; winter weather (heavy snow, blizzards, and hazardous winter conditions) at Medium risk — $159K in expected annual loss and about 14.95 events per year; and wildfire (uncontrolled fires that spread across wildland and into communities) at Low risk — $267K in expected annual loss and about 0.00 events per year. Across all hazards, FEMA estimates $8M in expected annual loss for a population of 6K.
Beyond physical exposure, Tripp County has a very high social vulnerability rating (how susceptible the population is to harm) and a medium 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.
The county's disaster history tells the same story: Tripp County has received 20 federal disaster declarations since 1976, including 8 for flood events and 6 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, Tripp County ranks #23 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Cold Wave | Medium | 5.47 / yr | $3M |
| Winter Weather | Medium | 14.95 / yr | $159K |
| Wildfire | Low | 0.00 / yr | $267K |
| Hail | Low | 3.89 / yr | $355K |
| Ice Storm | Low | 0.32 / yr | $77K |
| Drought | Low | 30.77 / yr | $149K |
| Tornado | Low | 0.55 / yr | $553K |
| Riverine Flood | Low | 0.93 / yr | $3M |
| Strong Wind | Low | 2.36 / yr | $200K |
| Heat Wave | Very Low | 4.05 / yr | $67K |
| Earthquake | Very Low | 0.00 / yr | $27K |
| Lightning | Very Low | 37.48 / yr | $48K |
| Landslide | Very Low | 0.35 / yr | $48 |
| 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
Tripp County has received 20 federal disaster declarations since 1976, most recently Severe Storms, Straight-Line Winds, and Flooding in August 2024. Most frequent causes: Flood (8), Severe Storm (6), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| August 2024 | Flood | Severe Storms, Straight-Line Winds, and Flooding |
| February 2023 | Winter Storm | Severe Winter Storms and Snowstorm |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| October 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 2010 | Flood | Flooding |
| March 2010 | Severe Storm | Severe Winter Storm and Snowstorm |
| July 2008 | Severe Storm | Severe Storms and Flooding |
Showing the 10 most recent of 20 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Tripp County?
Tripp County has a composite FEMA National Risk Index score of 36.5 out of 100, placing it in the Very Low category and the 36th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Tripp County?
The three highest-rated hazards are Cold Wave (Medium, $3M EAL), Winter Weather (Medium, $159K EAL), Wildfire (Low, $267K EAL). These account for most of the county's expected annual losses.
How does Tripp County compare to other South Dakota counties?
Tripp County ranks #23 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Tripp County had?
FEMA records 20 federal disaster declarations for Tripp County since 1976, most often 8 for flood events and 6 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. Tripp County's $8M EAL is a statistical average, not a guarantee for any specific year or address.