Johnson County
Iowa — Natural Disaster Risk Assessment
MediumComposite Risk Score
National percentile: 87th
Johnson County faces medium composite natural disaster risk (NRI Risk Index score 87.4, 87th national percentile), driven primarily by strong wind and tornado exposure. Expected annual loss across all 18 hazard types is $96M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Strong Wind | Very High | 6.41 / yr | $10M |
| Tornado | High | 0.59 / yr | $36M |
| Hail | High | 4.44 / yr | $4M |
| Cold Wave | High | 7.16 / yr | $10M |
| Winter Weather | High | 15.53 / yr | $492K |
| Heat Wave | Medium | 7.00 / yr | $4M |
| Drought | Medium | 12.89 / yr | $1M |
| Riverine Flood | Medium | 1.96 / yr | $27M |
| Landslide | Low | 0.20 / yr | $20K |
| Ice Storm | Medium | 0.46 / yr | $428K |
| Lightning | Medium | 44.31 / yr | $830K |
| Wildfire | Low | 0.00 / yr | $164K |
| Earthquake | Very Low | 0.00 / yr | $294K |
| Hurricane | Very Low | 0.01 / yr | $5K |
| 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 Johnson County?
Johnson County has a composite FEMA National Risk Index score of 87.4 out of 100, placing it in the Medium category and the 87th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Johnson County?
The three highest-rated hazards are Strong Wind (Very High, $10M EAL), Tornado (High, $36M EAL), Hail (High, $4M EAL). These account for most of the county's expected annual losses.
How does Johnson County compare to other Iowa counties?
Johnson County ranks #2 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. Johnson County's $96M EAL is a statistical average, not a guarantee for any specific year or address.