Union County Disaster Risk

Union County has a FEMA National Risk Index rating of Very Low, placing it in the 37th percentile nationally out of 3,144 counties. This composite score reflects the county's overall exposure to natural hazards including floods, wildfires, tornadoes, earthquakes, and hurricanes, weighted by expected annual loss and social vulnerability.

Union County is evaluated for five major natural hazard types: wildfire (78th percentile), tornado (69th percentile), flooding (47th percentile), earthquake (17th percentile). The highest-risk hazard is wildfire at the 78th percentile nationally. These scores are derived from FEMA's National Risk Index, which analyzes expected annual loss, social vulnerability, and community resilience for each hazard type.

Union County's composite risk percentile is 37th, compared to the South Dakota state average of 27th percentile. The state's overall risk rating is Very Low. This means Union County faces higher natural disaster risk than the typical county in South Dakota.

Yes, Union County's wildfire risk is at the 78th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Union County is at the 47th percentile.

FEMA's National Risk Index (NRI) calculates risk scores for 18 natural hazard types across all U.S. counties and census tracts. The composite score combines Expected Annual Loss (estimated dollar losses from each hazard), Social Vulnerability (demographic factors affecting disaster impact), and Community Resilience (ability to recover). Percentile scores rank each county against all 3,144 U.S. counties, and risk ratings range from Very Low to Very High.

Union County's composite risk score of 37th percentile is above the South Dakota state average of 27th percentile. This elevated risk is driven by wildfire exposure (78th percentile), along with tornado risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.