Stanislaus County, California Natural Disaster Risk
FEMA National Risk Index assessment · CA
HighComposite Risk Score
National percentile: 97th
Stanislaus County faces high composite natural disaster risk (NRI Risk Index score 96.9, 97th national percentile), driven primarily by drought and earthquake exposure. Expected annual loss across all 18 hazard types is $265M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Stanislaus County carries a high composite natural disaster risk, with a National Risk Index score of 96.9 out of 100 — placing it in the 97th 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 Stanislaus County's expected losses come from drought (extended dry periods that stress water supplies and agriculture) at Very High risk — $71M in expected annual loss and about 73.59 events per year; earthquake (ground shaking from sudden movement along geologic faults) at High risk — $85M in expected annual loss and about 0.07 events per year; and heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at Medium risk — $8M in expected annual loss and about 7.18 events per year. Across all hazards, FEMA estimates $265M in expected annual loss for a population of 553K.
Beyond physical exposure, Stanislaus County has a low social vulnerability rating (how susceptible the population is to harm) and a low community resilience rating (its capacity to prepare for and recover from disasters). Both measures sit toward the lower end, indicating relatively modest population sensitivity.
The county's disaster history tells the same story: Stanislaus County has received 20 federal disaster declarations since 1964, including 6 for flood events and 5 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, Stanislaus County ranks #23 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | Very High | 73.59 / yr | $71M |
| Earthquake | High | 0.07 / yr | $85M |
| Heat Wave | Medium | 7.18 / yr | $8M |
| Riverine Flood | High | 0.57 / yr | $94M |
| Wildfire | Medium | 0.01 / yr | $4M |
| Lightning | High | 6.95 / yr | $1M |
| Landslide | Low | 18.22 / yr | $39K |
| Volcanic Activity | Very Low | 0.00 / yr | $316 |
| Hail | Low | 0.09 / yr | $298K |
| Winter Weather | Low | 0.22 / yr | $41K |
| Strong Wind | Low | 0.04 / yr | $286K |
| Tornado | Low | 0.18 / yr | $462K |
| Avalanche | Very Low | 0.01 / yr | $3 |
| Coastal Flood | 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 |
| Tsunami | Very Low | 0.00 / yr | $0 |
Disaster History
Stanislaus County has received 20 federal disaster declarations since 1964, most recently Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides in April 2023. Most frequent causes: Flood (6), Severe Storm (5), Fire (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 |
| August 2020 | Fire | Wildfires |
| August 2020 | Fire | Scu Ligtning Complex Fire |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| April 2017 | Flood | Severe Winter Storms, Flooding, and Mudslides |
| March 2007 | Freezing | Severe Freeze |
Showing the 10 most recent of 20 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Stanislaus County?
Stanislaus County has a composite FEMA National Risk Index score of 96.9 out of 100, placing it in the High category and the 97th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Stanislaus County?
The three highest-rated hazards are Drought (Very High, $71M EAL), Earthquake (High, $85M EAL), Heat Wave (Medium, $8M EAL). These account for most of the county's expected annual losses.
How does Stanislaus County compare to other California counties?
Stanislaus County ranks #23 of 58 California counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has Stanislaus County had?
FEMA records 20 federal disaster declarations for Stanislaus County since 1964, most often 6 for flood events and 5 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. Stanislaus County's $265M EAL is a statistical average, not a guarantee for any specific year or address.