Colusa County, California Natural Disaster Risk
FEMA National Risk Index assessment · CA
MediumComposite Risk Score
National percentile: 81th
Colusa County faces medium composite natural disaster risk (NRI Risk Index score 81.1, 81th national percentile), driven primarily by drought and earthquake exposure. Expected annual loss across all 18 hazard types is $41M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Colusa County is medium, with a National Risk Index score of 81.1 out of 100 — placing it in the 81st 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 drought (extended dry periods that stress water supplies and agriculture) at Very High risk — $29M in expected annual loss and about 84.37 events per year; earthquake (ground shaking from sudden movement along geologic faults) at Medium risk — $5M in expected annual loss and about 0.05 events per year; and wildfire (uncontrolled fires that spread across wildland and into communities) at Medium risk — $1M in expected annual loss and about 0.01 events per year. Across all hazards, FEMA estimates $41M in expected annual loss for a population of 22K.
Beyond physical exposure, Colusa County has a medium 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 federal record bears this out: Colusa County has received 19 federal disaster declarations since 1964, including 7 for severe storm events and 6 for flood events. The most recent was Severe Winter Storms, Flooding, Landslides, and Mudslides (flood), declared in January 2023.
Among 58 California counties, Colusa County ranks #48 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | Very High | 84.37 / yr | $29M |
| Earthquake | Medium | 0.05 / yr | $5M |
| Wildfire | Medium | 0.01 / yr | $1M |
| Landslide | Low | 16.73 / yr | $6K |
| Heat Wave | Low | 7.60 / yr | $679K |
| Volcanic Activity | Very Low | 0.00 / yr | $5 |
| Riverine Flood | Low | 0.54 / yr | $4M |
| Lightning | Very Low | 6.06 / yr | $50K |
| Avalanche | Very Low | 0.01 / yr | $7 |
| Tornado | Very Low | 0.13 / yr | $51K |
| Hail | Very Low | 0.07 / yr | $16K |
| Strong Wind | Very Low | 0.02 / yr | $23K |
| Winter Weather | Very Low | 4.21 / yr | $476 |
| 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
Colusa County has received 19 federal disaster declarations since 1964, most recently Severe Winter Storms, Flooding, Landslides, and Mudslides in January 2023. Most frequent causes: Severe Storm (7), Flood (6), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| 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 |
| May 2019 | Severe Storm | Severe Winter Storms, Flooding, Landslides, and Mudslides |
| May 2019 | Severe Storm | Severe Winter Storms, Flooding, Landslides, and Mudslides |
| April 2017 | Flood | Severe Winter Storms, Flooding, and Mudslides |
| February 2006 | Severe Storm | Severe Storms, Flooding, Mudslides, and Landslides |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| February 1998 | Severe Storm | Severe Winter Storms and Flooding |
Showing the 10 most recent of 19 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Colusa County?
Colusa County has a composite FEMA National Risk Index score of 81.1 out of 100, placing it in the Medium category and the 81th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Colusa County?
The three highest-rated hazards are Drought (Very High, $29M EAL), Earthquake (Medium, $5M EAL), Wildfire (Medium, $1M EAL). These account for most of the county's expected annual losses.
How does Colusa County compare to other California counties?
Colusa County ranks #48 of 58 California counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Colusa County had?
FEMA records 19 federal disaster declarations for Colusa County since 1964, most often 7 for severe storm events and 6 for flood events. The most recent was Severe Winter Storms, Flooding, Landslides, and Mudslides, declared in January 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. Colusa County's $41M EAL is a statistical average, not a guarantee for any specific year or address.