Polk County Disaster Risk

Polk County has a FEMA National Risk Index rating of Relatively Moderate, placing it in the 92th 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.

Polk County is evaluated for five major natural hazard types: tornado (98th percentile), flooding (92th percentile), earthquake (67th percentile), wildfire (58th percentile), hurricane (27th percentile). The highest-risk hazard is tornado at the 98th 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.

Polk County's composite risk percentile is 92th, compared to the Iowa state average of 40th percentile. The state's overall risk rating is Very Low. This means Polk County faces higher natural disaster risk than the typical county in Iowa.

Yes, Polk County's tornado risk is at the 98th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Polk County is at the 92th 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.

Polk County's composite risk score of 92th percentile is above the Iowa state average of 40th percentile. This elevated risk is driven by tornado exposure (98th percentile), along with flooding and earthquake and wildfire risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.