Polk County
Iowa — Natural Disaster Risk Assessment
MediumComposite Risk Score
National percentile: 92th
Polk County faces medium composite natural disaster risk (NRI Risk Index score 92.0, 92th national percentile), driven primarily by strong wind and tornado exposure. Expected annual loss across all 18 hazard types is $138M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Strong Wind | Very High | 6.01 / yr | $11M |
| Tornado | High | 0.59 / yr | $31M |
| Hail | High | 6.13 / yr | $7M |
| Heat Wave | High | 7.32 / yr | $11M |
| Drought | High | 6.46 / yr | $3M |
| Riverine Flood | Medium | 5.07 / yr | $61M |
| Ice Storm | High | 0.93 / yr | $1M |
| Cold Wave | High | 6.00 / yr | $10M |
| Winter Weather | High | 14.11 / yr | $506K |
| Lightning | Medium | 44.35 / yr | $816K |
| Landslide | Low | 0.12 / yr | $6K |
| Earthquake | Low | 0.00 / yr | $820K |
| Wildfire | Very Low | 0.00 / yr | $91K |
| Hurricane | Very Low | 0.01 / yr | $14K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Polk County?
Polk County has a composite FEMA National Risk Index score of 92.0 out of 100, placing it in the Medium category and the 92th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Polk County?
The three highest-rated hazards are Strong Wind (Very High, $11M EAL), Tornado (High, $31M EAL), Hail (High, $7M EAL). These account for most of the county's expected annual losses.
How does Polk County compare to other Iowa counties?
Polk County ranks #1 of 99 Iowa counties for overall natural disaster risk, with a medium rating.
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. Polk County's $138M EAL is a statistical average, not a guarantee for any specific year or address.