Contra Costa County
California — Natural Disaster Risk Assessment
Very HighComposite Risk Score
National percentile: 99th
Contra Costa County faces very high composite natural disaster risk (NRI Risk Index score 99.5, 99th national percentile), driven primarily by earthquake and riverine flood exposure. Expected annual loss across all 18 hazard types is $971M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Earthquake | High | 0.13 / yr | $519M |
| Riverine Flood | Very High | 1.18 / yr | $412M |
| Landslide | High | 19.83 / yr | $2M |
| Heat Wave | High | 8.49 / yr | $18M |
| Wildfire | Medium | 0.00 / yr | $11M |
| Drought | High | 55.93 / yr | $3M |
| Lightning | High | 4.45 / yr | $1M |
| Volcanic Activity | Very Low | 0.00 / yr | $343 |
| Coastal Flood | Medium | 1.53 / yr | $1M |
| Tornado | Low | 0.10 / yr | $1M |
| Tsunami | Low | 0.34 / yr | $1M |
| Strong Wind | Low | 0.04 / yr | $398K |
| Hail | Very Low | 0.04 / yr | $157K |
| Winter Weather | Very Low | 0.44 / yr | $8K |
| Avalanche | Very Low | 0.01 / yr | $3 |
| Cold Wave | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Ice Storm | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Contra Costa County?
Contra Costa County has a composite FEMA National Risk Index score of 99.5 out of 100, placing it in the Very High category and the 99th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Contra Costa County?
The three highest-rated hazards are Earthquake (High, $519M EAL), Riverine Flood (Very High, $412M EAL), Landslide (High, $2M EAL). These account for most of the county's expected annual losses.
How does Contra Costa County compare to other California counties?
Contra Costa County ranks #8 of 58 California counties for overall natural disaster risk, with a very high 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. Contra Costa County's $971M EAL is a statistical average, not a guarantee for any specific year or address.