Boulder County, Colorado Natural Disaster Risk
FEMA National Risk Index assessment · CO
MediumComposite Risk Score
National percentile: 91th
Boulder County faces medium composite natural disaster risk (NRI Risk Index score 90.7, 91th national percentile), driven primarily by lightning and hail exposure. Expected annual loss across all 18 hazard types is $125M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Boulder County carries a medium composite natural disaster risk, with a National Risk Index score of 90.7 out of 100 — placing it in the 91st 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.
Most of Boulder County's expected losses come from lightning (electrical discharges from storms that ignite fires and cause casualties) at Very High risk — $6M in expected annual loss and about 54.13 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at High risk — $10M in expected annual loss and about 5.48 events per year; and wildfire (uncontrolled fires that spread across wildland and into communities) at High risk — $16M in expected annual loss and about 0.01 events per year. Across all hazards, FEMA estimates $125M in expected annual loss for a population of 331K.
Beyond physical exposure, Boulder County has a very low 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 county's disaster history tells the same story: Boulder County has received 19 federal disaster declarations since 1969, including 9 for fire events and 5 for flood events. The most recent was Stone Mountain Fire (fire), declared in July 2024.
Among 64 Colorado counties, Boulder County ranks #6 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Lightning | Very High | 54.13 / yr | $6M |
| Hail | High | 5.48 / yr | $10M |
| Wildfire | High | 0.01 / yr | $16M |
| Winter Weather | High | 21.40 / yr | $1M |
| Tornado | High | 0.52 / yr | $12M |
| Riverine Flood | Medium | 0.75 / yr | $69M |
| Landslide | Medium | 0.27 / yr | $78K |
| Avalanche | High | 0.63 / yr | $2M |
| Strong Wind | High | 1.00 / yr | $2M |
| Earthquake | Low | 0.00 / yr | $2M |
| Ice Storm | Medium | 0.01 / yr | $354K |
| Cold Wave | Medium | 0.59 / yr | $3M |
| Volcanic Activity | Very Low | 0.00 / yr | $79 |
| Heat Wave | Low | 0.31 / yr | $815K |
| Drought | Low | 11.23 / yr | $79K |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
Disaster History
Boulder County has received 19 federal disaster declarations since 1969, most recently Stone Mountain Fire in July 2024. Most frequent causes: Fire (9), Flood (5), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| July 2024 | Fire | Stone Mountain Fire |
| December 2021 | Fire | Wildfires and Straight-Line Winds |
| December 2021 | Fire | Marshall Fire |
| October 2020 | Fire | Calwood Fire |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2015 | Flood | Severe Storms, Tornadoes, Flooding, Landslides, and Mudslides |
| September 2013 | Flood | Severe Storms, Flooding, Landslides, and Mudslides |
| September 2013 | Flood | Severe Storms, Flooding, Landslides, and Mudslides |
| September 2010 | Fire | Four Mile Canyon Fire |
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 Boulder County?
Boulder County has a composite FEMA National Risk Index score of 90.7 out of 100, placing it in the Medium category and the 91th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Boulder County?
The three highest-rated hazards are Lightning (Very High, $6M EAL), Hail (High, $10M EAL), Wildfire (High, $16M EAL). These account for most of the county's expected annual losses.
How does Boulder County compare to other Colorado counties?
Boulder County ranks #6 of 64 Colorado counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Boulder County had?
FEMA records 19 federal disaster declarations for Boulder County since 1969, most often 9 for fire events and 5 for flood events. The most recent was Stone Mountain 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. Boulder County's $125M EAL is a statistical average, not a guarantee for any specific year or address.