California tsunami risk
Del Norte County has the highest tsunami risk in California, scoring 98.5 out of 100 — rated "Very High" by FEMA's National Risk Index.
| # | County | NRI score | Rating |
|---|---|---|---|
| 1 | Del Norte County | 98.5 | Very High |
| 2 | Humboldt County | 93.8 | Relatively High |
| 3 | Santa Cruz County | 73.8 | Relatively Moderate |
| 4 | San Francisco County | 72.3 | Relatively Moderate |
| 5 | San Mateo County | 70.8 | Relatively Moderate |
| 6 | Marin County | 69.2 | Relatively Moderate |
| 7 | Los Angeles County | 64.6 | Relatively Low |
| 8 | San Luis Obispo County | 63.1 | Relatively Low |
| 9 | Alameda County | 60 | Relatively Low |
| 10 | Orange County | 56.9 | Relatively Low |
| 11 | San Diego County | 52.3 | Relatively Low |
| 12 | Contra Costa County | 47.7 | Relatively Low |
| 13 | Monterey County | 46.2 | Very Low |
| 14 | Ventura County | 44.6 | Very Low |
| 15 | Santa Barbara County | 38.5 | Very Low |
| 16 | Mendocino County | 32.3 | Very Low |
| 17 | Sonoma County | 26.2 | Very Low |
| 18 | Santa Clara County | 18.5 | Very Low |
| 19 | Solano County | 15.4 | Very Low |
| 20 | Napa County | 3.1 | Very Low |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Tsunami risk nationally:
Other hazard risks in California:
Frequently asked questions
What is the highest tsunami risk county in California?
Del Norte County, CA has the highest tsunami risk in California, with a FEMA National Risk Index score of 98.5 out of 100 (rated "Very High").
How many counties in California are rated Very High for tsunami risk?
1 of 20 scored California counties are rated "Very High" for tsunami risk by FEMA's National Risk Index.
What causes tsunami risk in California?
Tsunami risk covers expected losses from seismically generated ocean waves. Risk concentrates on the Pacific Coast — especially Oregon, Washington, and Alaska — where the Cascadia Subduction Zone and other fault systems can generate destructive local tsunamis with little warning. Atlantic and Gulf coasts carry lower but non-zero risk from distant earthquake sources.