Jefferson County, Colorado Natural Disaster Risk
FEMA National Risk Index assessment · CO
HighComposite Risk Score
National percentile: 95th
Jefferson County faces high composite natural disaster risk (NRI Risk Index score 94.9, 95th national percentile), driven primarily by hail and lightning exposure. Expected annual loss across all 18 hazard types is $231M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Jefferson County at high composite risk, with a National Risk Index score of 94.9 out of 100 — placing it in the 95th 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 Jefferson County's expected losses come from hail (ice stones from severe thunderstorms that damage property and crops) at Very High risk — $58M in expected annual loss and about 6.86 events per year; lightning (electrical discharges from storms that ignite fires and cause casualties) at Very High risk — $11M in expected annual loss and about 57.73 events per year; and wildfire (uncontrolled fires that spread across wildland and into communities) at High risk — $49M in expected annual loss and about 0.01 events per year. Across all hazards, FEMA estimates $231M in expected annual loss for a population of 583K.
Beyond physical exposure, Jefferson County has a very low social vulnerability rating (how susceptible the population is to harm) and a 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: Jefferson County has received 15 federal disaster declarations since 1969, including 5 for fire events and 5 for flood events. The most recent was Quarry Fire (fire), declared in August 2024.
Among 64 Colorado counties, Jefferson County ranks #2 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Hail | Very High | 6.86 / yr | $58M |
| Lightning | Very High | 57.73 / yr | $11M |
| Wildfire | High | 0.01 / yr | $49M |
| Winter Weather | Very High | 18.90 / yr | $2M |
| Landslide | Medium | 0.41 / yr | $559K |
| Tornado | High | 0.56 / yr | $22M |
| Riverine Flood | High | 1.29 / yr | $77M |
| Strong Wind | High | 0.95 / yr | $3M |
| Earthquake | Low | 0.00 / yr | $3M |
| Avalanche | Low | 0.40 / yr | $131K |
| Cold Wave | Medium | 0.38 / yr | $3M |
| Ice Storm | Medium | 0.01 / yr | $325K |
| Heat Wave | Low | 0.18 / yr | $1M |
| Volcanic Activity | Very Low | 0.00 / yr | $139 |
| Drought | Very Low | 22.56 / yr | $24K |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
Disaster History
Jefferson County has received 15 federal disaster declarations since 1969, most recently Quarry Fire in August 2024. Most frequent causes: Fire (5), Flood (5), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| August 2024 | Fire | Quarry Fire |
| August 2023 | Flood | Severe Storms, Flooding, and Tornadoes |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| September 2013 | Flood | Severe Storms, Flooding, Landslides, and Mudslides |
| September 2013 | Flood | Severe Storms, Flooding, Landslides, and Mudslides |
| March 2012 | Fire | Lower North Fork Fire |
| March 2011 | Fire | Indian Gulch Fire |
| January 2007 | Snowstorm | Snow |
| September 2005 | Coastal Storm | Hurricane Katrina Evacuation |
Showing the 10 most recent of 15 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Jefferson County?
Jefferson County has a composite FEMA National Risk Index score of 94.9 out of 100, placing it in the High category and the 95th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Jefferson County?
The three highest-rated hazards are Hail (Very High, $58M EAL), Lightning (Very High, $11M EAL), Wildfire (High, $49M EAL). These account for most of the county's expected annual losses.
How does Jefferson County compare to other Colorado counties?
Jefferson County ranks #2 of 64 Colorado counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has Jefferson County had?
FEMA records 15 federal disaster declarations for Jefferson County since 1969, most often 5 for fire events and 5 for flood events. The most recent was Quarry Fire, declared in August 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. Jefferson County's $231M EAL is a statistical average, not a guarantee for any specific year or address.