San Francisco County, California Natural Disaster Risk
FEMA National Risk Index assessment · CA
Very HighComposite Risk Score
National percentile: 100th
San Francisco County faces very high composite natural disaster risk (NRI Risk Index score 99.5, 100th national percentile), driven primarily by earthquake and riverine flood exposure. Expected annual loss across all 18 hazard types is $853M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
San Francisco County carries a very high composite natural disaster risk, with a National Risk Index score of 99.5 out of 100 — placing it in the 100th national percentile and among the most at-risk counties in the United States. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
The county's risk is driven primarily by earthquake (ground shaking from sudden movement along geologic faults) at Very High risk — $662M in expected annual loss and about 0.10 events per year; riverine flood (rivers and streams overflowing their banks after heavy rain or snowmelt) at High risk — $178M in expected annual loss and about 1.61 events per year; and landslide (downhill movement of rock, soil, and debris on unstable slopes) at High risk — $829K in expected annual loss and about 0.22 events per year. Across all hazards, FEMA estimates $853M in expected annual loss for a population of 874K.
Beyond physical exposure, San Francisco County has a medium social vulnerability rating (how susceptible the population is to harm) and a very 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 federal record bears this out: San Francisco County has received 11 federal disaster declarations since 1989, including 4 for severe storm events and 3 for flood 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, San Francisco County ranks #9 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Earthquake | Very High | 0.10 / yr | $662M |
| Riverine Flood | High | 1.61 / yr | $178M |
| Landslide | High | 0.22 / yr | $829K |
| Heat Wave | Medium | 3.46 / yr | $5M |
| Tsunami | Medium | 0.34 / yr | $6M |
| Drought | Medium | 26.45 / yr | $488K |
| Coastal Flood | Medium | 1.00 / yr | $638K |
| Tornado | Low | 0.01 / yr | $652K |
| Lightning | Low | 3.80 / yr | $104K |
| Wildfire | Very Low | 0.00 / yr | $13K |
| Volcanic Activity | Very Low | 0.00 / yr | $1 |
| Hail | Very Low | 0.02 / yr | $62K |
| Strong Wind | Very Low | 0.03 / yr | $74K |
| Winter Weather | Very Low | 0.00 / yr | $0 |
| Avalanche | Very Low | 0.00 / yr | $0 |
| 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
San Francisco County has received 11 federal disaster declarations since 1989, most recently Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides in April 2023. Most frequent causes: Severe Storm (4), Flood (3), Biological (2).
| 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 |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| February 1998 | Severe Storm | Severe Winter Storms and Flooding |
| January 1997 | Severe Storm | Severe Storms, Flooding, Mud and Landslides |
| March 1995 | Severe Storm | Severe Winter Storms, Flooding Landslides, Mud Flow |
Showing the 10 most recent of 11 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for San Francisco County?
San Francisco County has a composite FEMA National Risk Index score of 99.5 out of 100, placing it in the Very High category and the 100th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in San Francisco County?
The three highest-rated hazards are Earthquake (Very High, $662M EAL), Riverine Flood (High, $178M EAL), Landslide (High, $829K EAL). These account for most of the county's expected annual losses.
How does San Francisco County compare to other California counties?
San Francisco County ranks #9 of 58 California counties for overall natural disaster risk, with a very high rating.
How many federally declared disasters has San Francisco County had?
FEMA records 11 federal disaster declarations for San Francisco County since 1989, most often 4 for severe storm events and 3 for flood 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. San Francisco County's $853M EAL is a statistical average, not a guarantee for any specific year or address.