Ada County
Idaho — Natural Disaster Risk Assessment
MediumComposite Risk Score
National percentile: 88th
Ada County faces medium composite natural disaster risk (NRI Risk Index score 87.8, 88th national percentile), driven primarily by winter weather and wildfire exposure. Expected annual loss across all 18 hazard types is $116M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Winter Weather | Very High | 8.86 / yr | $3M |
| Wildfire | High | 0.01 / yr | $27M |
| Heat Wave | Medium | 4.37 / yr | $7M |
| Strong Wind | High | 0.33 / yr | $4M |
| Lightning | High | 19.81 / yr | $2M |
| Riverine Flood | Medium | 0.79 / yr | $63M |
| Earthquake | Low | 0.00 / yr | $7M |
| Ice Storm | Medium | 0.10 / yr | $706K |
| Volcanic Activity | Very Low | 0.00 / yr | $235 |
| Landslide | Low | 0.15 / yr | $9K |
| Hail | Low | 0.24 / yr | $525K |
| Cold Wave | Low | 0.11 / yr | $2M |
| Avalanche | Very Low | 0.01 / yr | $132 |
| Tornado | Low | 0.06 / yr | $686K |
| Drought | Very Low | 14.29 / yr | $783 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Ada County?
Ada County has a composite FEMA National Risk Index score of 87.8 out of 100, placing it in the Medium category and the 88th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Ada County?
The three highest-rated hazards are Winter Weather (Very High, $3M EAL), Wildfire (High, $27M EAL), Heat Wave (Medium, $7M EAL). These account for most of the county's expected annual losses.
How does Ada County compare to other Idaho counties?
Ada County ranks #1 of 44 Idaho 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. Ada County's $116M EAL is a statistical average, not a guarantee for any specific year or address.