Clark County, South Dakota Natural Disaster Risk
FEMA National Risk Index assessment · SD
Very LowComposite Risk Score
National percentile: 5th
Clark County faces very low composite natural disaster risk (NRI Risk Index score 4.5, 5th national percentile), driven primarily by cold wave and hail exposure. Expected annual loss across all 18 hazard types is $4M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Clark County is very low, with a National Risk Index score of 4.5 out of 100 — placing it in the 5th 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 Clark County's expected losses come from cold wave (prolonged spells of dangerously low temperatures) at Low risk — $2M in expected annual loss and about 12.47 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at Low risk — $445K in expected annual loss and about 4.30 events per year; and ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Low risk — $130K in expected annual loss and about 0.49 events per year. Across all hazards, FEMA estimates $4M in expected annual loss for a population of 4K.
Beyond physical exposure, Clark County has a very 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 county's disaster history tells the same story: Clark County has received 22 federal disaster declarations since 1976, including 9 for flood events and 7 for severe storm events. The most recent was Flooding (flood), declared in July 2023.
Among 66 South Dakota counties, Clark County ranks #60 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Cold Wave | Low | 12.47 / yr | $2M |
| Hail | Low | 4.30 / yr | $445K |
| Ice Storm | Low | 0.49 / yr | $130K |
| Wildfire | Very Low | 0.00 / yr | $74K |
| Winter Weather | Low | 22.00 / yr | $67K |
| Tornado | Very Low | 0.54 / yr | $436K |
| Landslide | Very Low | 0.11 / yr | $183 |
| Heat Wave | Very Low | 3.21 / yr | $62K |
| Strong Wind | Very Low | 3.09 / yr | $133K |
| Riverine Flood | Very Low | 0.75 / yr | $1M |
| Earthquake | Very Low | 0.00 / yr | $6K |
| Lightning | Very Low | 33.58 / yr | $3K |
| 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
Clark County has received 22 federal disaster declarations since 1976, most recently Flooding in July 2023. Most frequent causes: Flood (9), Severe Storm (7), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| July 2023 | Flood | Flooding |
| February 2023 | Winter Storm | Severe Winter Storms and Snowstorm |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| November 2019 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| June 2019 | Flood | Severe Winter Storm, Snowstorm, and Flooding |
| February 2017 | Severe Storm | Severe Winter Storm |
| May 2011 | Flood | Flooding |
| May 2010 | Flood | Flooding |
| May 2007 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
Showing the 10 most recent of 22 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Clark County?
Clark County has a composite FEMA National Risk Index score of 4.5 out of 100, placing it in the Very Low category and the 5th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Clark County?
The three highest-rated hazards are Cold Wave (Low, $2M EAL), Hail (Low, $445K EAL), Ice Storm (Low, $130K EAL). These account for most of the county's expected annual losses.
How does Clark County compare to other South Dakota counties?
Clark County ranks #60 of 66 South Dakota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Clark County had?
FEMA records 22 federal disaster declarations for Clark County since 1976, most often 9 for flood events and 7 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. Clark County's $4M EAL is a statistical average, not a guarantee for any specific year or address.