Mariposa County, California Natural Disaster Risk
FEMA National Risk Index assessment · CA
MediumComposite Risk Score
National percentile: 86th
Mariposa County faces medium composite natural disaster risk (NRI Risk Index score 86.4, 86th national percentile), driven primarily by landslide and wildfire exposure. Expected annual loss across all 18 hazard types is $38M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Mariposa County at medium composite risk, with a National Risk Index score of 86.4 out of 100 — placing it in the 86th national percentile and near the national midpoint for natural-disaster risk. 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 landslide (downhill movement of rock, soil, and debris on unstable slopes) at High risk — $2M in expected annual loss and about 27.38 events per year; wildfire (uncontrolled fires that spread across wildland and into communities) at High risk — $15M in expected annual loss and about 0.02 events per year; and heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at High risk — $11M in expected annual loss and about 6.05 events per year. Across all hazards, FEMA estimates $38M in expected annual loss for a population of 17K.
Beyond physical exposure, Mariposa County has a very high 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). That combination — a more vulnerable population with limited resilience — can amplify the human cost of any given event.
The federal record bears this out: Mariposa County has received 24 federal disaster declarations since 1969, including 9 for fire events and 5 for severe storm events. The most recent was French Fire (fire), declared in July 2024.
Among 58 California counties, Mariposa County ranks #43 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Landslide | High | 27.38 / yr | $2M |
| Wildfire | High | 0.02 / yr | $15M |
| Heat Wave | High | 6.05 / yr | $11M |
| Winter Weather | Medium | 12.67 / yr | $113K |
| Drought | Medium | 83.16 / yr | $448K |
| Riverine Flood | Low | 2.07 / yr | $8M |
| Lightning | Medium | 17.91 / yr | $302K |
| Earthquake | Low | 0.03 / yr | $433K |
| Volcanic Activity | Very Low | 0.00 / yr | $17 |
| Avalanche | Very Low | 0.01 / yr | $171 |
| Strong Wind | Very Low | 0.05 / yr | $50K |
| Hail | Very Low | 0.15 / yr | $12K |
| Tornado | Very Low | 0.12 / yr | $18K |
| 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
Mariposa County has received 24 federal disaster declarations since 1969, most recently French Fire in July 2024. Most frequent causes: Fire (9), Severe Storm (5), Flood (5).
| Declared | Type | Disaster |
|---|---|---|
| July 2024 | Fire | French Fire |
| 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 |
| July 2022 | Fire | Oak Fire |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| May 2019 | Severe Storm | Severe Winter Storms, Flooding, Landslides, and Mudslides |
| May 2019 | Severe Storm | Severe Winter Storms, Flooding, Landslides, and Mudslides |
Showing the 10 most recent of 24 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Mariposa County?
Mariposa County has a composite FEMA National Risk Index score of 86.4 out of 100, placing it in the Medium category and the 86th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Mariposa County?
The three highest-rated hazards are Landslide (High, $2M EAL), Wildfire (High, $15M EAL), Heat Wave (High, $11M EAL). These account for most of the county's expected annual losses.
How does Mariposa County compare to other California counties?
Mariposa County ranks #43 of 58 California counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Mariposa County had?
FEMA records 24 federal disaster declarations for Mariposa County since 1969, most often 9 for fire events and 5 for severe storm events. The most recent was French Fire, declared in July 2024.
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. Mariposa County's $38M EAL is a statistical average, not a guarantee for any specific year or address.