Sioux County
Iowa — Natural Disaster Risk Assessment
LowComposite Risk Score
National percentile: 52th
Sioux County faces low composite natural disaster risk (NRI Risk Index score 52.4, 52th national percentile), driven primarily by hail and winter weather exposure. Expected annual loss across all 18 hazard types is $30M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Hail | High | 6.49 / yr | $6M |
| Winter Weather | High | 16.84 / yr | $557K |
| Tornado | Medium | 0.68 / yr | $7M |
| Ice Storm | Medium | 0.97 / yr | $421K |
| Drought | Medium | 24.38 / yr | $1M |
| Cold Wave | Low | 7.53 / yr | $3M |
| Riverine Flood | Low | 3.29 / yr | $11M |
| Strong Wind | Low | 4.39 / yr | $934K |
| Heat Wave | Low | 5.89 / yr | $412K |
| Wildfire | Very Low | 0.00 / yr | $44K |
| Landslide | Very Low | 0.08 / yr | $538 |
| Lightning | Low | 39.38 / yr | $187K |
| Earthquake | Very Low | 0.00 / yr | $46K |
| 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 |
Frequently Asked Questions
What is the overall natural disaster risk for Sioux County?
Sioux County has a composite FEMA National Risk Index score of 52.4 out of 100, placing it in the Low category and the 52th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Sioux County?
The three highest-rated hazards are Hail (High, $6M EAL), Winter Weather (High, $557K EAL), Tornado (Medium, $7M EAL). These account for most of the county's expected annual losses.
How does Sioux County compare to other Iowa counties?
Sioux County ranks #23 of 99 Iowa counties for overall natural disaster risk, with a low 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. Sioux County's $30M EAL is a statistical average, not a guarantee for any specific year or address.