Sonoma County, California Natural Disaster Risk
FEMA National Risk Index assessment · CA
HighComposite Risk Score
National percentile: 99th
Sonoma County faces high composite natural disaster risk (NRI Risk Index score 99.1, 99th national percentile), driven primarily by landslide and earthquake exposure. Expected annual loss across all 18 hazard types is $605M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Sonoma County at high composite risk, with a National Risk Index score of 99.1 out of 100 — placing it in the 99th national percentile and in the upper tier of natural-disaster risk nationally. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Sonoma County's expected losses come from landslide (downhill movement of rock, soil, and debris on unstable slopes) at High risk — $5M in expected annual loss and about 67.44 events per year; earthquake (ground shaking from sudden movement along geologic faults) at High risk — $284M in expected annual loss and about 0.12 events per year; and drought (extended dry periods that stress water supplies and agriculture) at High risk — $14M in expected annual loss and about 33.50 events per year. Across all hazards, FEMA estimates $605M in expected annual loss for a population of 488K.
Beyond physical exposure, Sonoma County has a low social vulnerability rating (how susceptible the population is to harm) and a high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
The county's disaster history tells the same story: Sonoma County has received 36 federal disaster declarations since 1964, including 11 for fire events and 9 for severe storm events. The most recent was Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides (severe storm), declared in April 2023.
Among 58 California counties, Sonoma County ranks #13 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Landslide | High | 67.44 / yr | $5M |
| Earthquake | High | 0.12 / yr | $284M |
| Drought | High | 33.50 / yr | $14M |
| Riverine Flood | High | 2.54 / yr | $280M |
| Wildfire | High | 0.00 / yr | $17M |
| Heat Wave | Medium | 7.00 / yr | $3M |
| Volcanic Activity | Low | 0.00 / yr | $3K |
| Coastal Flood | Medium | 3.42 / yr | $1M |
| Lightning | Medium | 3.73 / yr | $341K |
| Tsunami | Very Low | 0.34 / yr | $244K |
| Hail | Very Low | 0.02 / yr | $60K |
| Tornado | Very Low | 0.08 / yr | $163K |
| Strong Wind | Very Low | 0.02 / yr | $119K |
| Avalanche | Very Low | 0.01 / yr | $10 |
| Winter Weather | Very Low | 0.74 / yr | $6K |
| Cold Wave | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Ice Storm | Very Low | 0.00 / yr | $0 |
Disaster History
Sonoma County has received 36 federal disaster declarations since 1964, most recently Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides in April 2023. Most frequent causes: Fire (11), Severe Storm (9), Flood (9).
| Declared | Type | Disaster |
|---|---|---|
| April 2023 | Severe Storm | Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides |
| March 2023 | Flood | Severe Winter Storms, Flooding, Landslides, and Mudslides |
| January 2023 | Flood | Severe Winter Storms, Flooding, Landslides, and Mudslides |
| January 2023 | Flood | Severe Winter Storms, Flooding, and Mudslides |
| October 2020 | Fire | Wildfires |
| September 2020 | Fire | Glass Fire |
| August 2020 | Fire | Wildfires |
| August 2020 | Fire | Lnu Lightning Fire Complex |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
Showing the 10 most recent of 36 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Sonoma County?
Sonoma County has a composite FEMA National Risk Index score of 99.1 out of 100, placing it in the 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 Sonoma County?
The three highest-rated hazards are Landslide (High, $5M EAL), Earthquake (High, $284M EAL), Drought (High, $14M EAL). These account for most of the county's expected annual losses.
How does Sonoma County compare to other California counties?
Sonoma County ranks #13 of 58 California counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has Sonoma County had?
FEMA records 36 federal disaster declarations for Sonoma County since 1964, most often 11 for fire events and 9 for severe storm events. The most recent was Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides, declared in April 2023.
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. Sonoma County's $605M EAL is a statistical average, not a guarantee for any specific year or address.