Arapahoe County, Colorado: Natural Disaster Risk and History
Arapahoe County, Colorado has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 93.8 out of 100, higher than about 93% of US counties, with hail, lightning and tornadoes scoring highest of its 18 hazards and $172 million a year in expected losses.
OpenFEMA lists 10 federal disaster declarations that included Arapahoe County since 1965, not counting 2 for COVID-19; the latest is DR-4731-CO (Severe Storms, Flooding, and Tornadoes, declared 25 August 2023). NOAA's Storm Prediction Center recorded 103 tornadoes touching Arapahoe County from 1950 to 2025.
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Population 654,201 Buildings worth $120 billion Area 814 sq mi Risk rank in Colorado 4 of 64 FIPS 08005
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Hail | Very High | 99.8 | $64 million | about 8.6 a year | 327 |
| Lightning | Very High | 98.4 | $4.0 million | about 52 a year | 433,347 strikes |
| Tornado | Relatively High | 97.2 | $22 million | about 1.1 a year | 73 |
| Strong wind | Relatively High | 95.1 | $3.7 million | about 1.4 a year | 55 |
| Inland flooding | Relatively Moderate | 92.5 | $62 million | about 1.3 a year | 37 |
| Cold wave | Relatively High | 91.1 | $9.4 million | about 1.6 a year | 31 |
| Winter weather | Relatively High | 91.1 | $518,786 | about 13 a year | 241 |
| Earthquake | Relatively Low | 85.5 | $3.5 million | rarer than once in 1,000 years | — |
| Wildfire | Relatively Low | 84.7 | $802,120 | about once every 671 years | — |
| Volcanic activity | Very Low | 73.0 | $155 | rarer than once in 1,000 years | 1 |
| Heat wave | Relatively Low | 68.6 | $1.0 million | about once every 1.4 years | 11 |
| Landslide | Very Low | 50.5 | $1,652 | about once every 6.6 years | — |
| Drought | Relatively Low | 44.6 | $117,648 | about 29 a year | 1,008 |
| Ice storm | Very Low | 11.4 | $7,305 | about once every 38 years | 2 |
| Avalanche | Not Applicable | — | — | — | — |
| Coastal flooding | Not Applicable | — | — | — | — |
| Hurricane | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 10
Most common: Flood 5, Snowstorm 2, Coastal Storm 1, Fire 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1960s | 2 | Flood, Tornado |
| 1970s | 1 | Flood |
| 2000s | 4 | Snowstorm ×2, Coastal Storm, Fire |
| 2010s | 2 | Flood ×2 |
| 2020s | 1 | Flood |
The last 10
Widest declarations that included Arapahoe County
- Hurricane Katrina Evacuation (2005, EM-3224-CO): 64 Colorado counties designated.
- Wildfires (2002, DR-1421-CO): 58 Colorado counties designated.
- Snow (2003, EM-3185-CO): 29 Colorado counties designated.
Named storms in its declarations: Hurricane Katrina (2005).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. Colorado also had 12 statewide declarations with no county list.
Tornado record since 1950 103
| Tornadoes touching the county | 103 |
|---|---|
| Strongest-rated | (E)F2 ×3 |
| Peak month | June (35) |
| Deadliest | 8 Jun 1986, F2, 1.1 mi path, 0 killed, 6 injured |
| Longest path | 7 Jun 2009, EF1, 5.5 mi path, 0 killed, 2 injured |
| Most recent | 10 Aug 2025, unrated, 0.4 mi path |
| Deaths / injuries on those paths | 0 / 11 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 65 | 32 | 3 | 0 | 0 | 0 | 3 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 0 | 10 | 9 | 22 | 30 | 11 | 14 | 7 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Arapahoe County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Arapahoe County (this page) | — | Relatively Moderate | 93.8 | Hail |
| Adams County | 25 km | Relatively Moderate | 91.2 | Hail |
| Elbert County | 44 km | Very Low | 36.6 | Wildfire |
| Denver County | 48 km | Relatively High | 95.2 | Hail |
| Douglas County | 62 km | Relatively Moderate | 88.7 | Lightning |
| Broomfield County | 70 km | Very Low | 34.7 | Hail |
Nearest by distance between county centres. Every county in Colorado, ranked.
Vulnerability and resilience
| Social vulnerability | Very Low 18.4 |
|---|---|
| Community resilience | Relatively Moderate 49.4 |
| Community risk factor | 0.88 |
| Expected annual loss, all hazards | $172 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Arapahoe County's main hazards
- Right now: National Weather Service alerts for Colorado · all official warnings on Global Incident Tracker.
- Hail: Weather alerts for Colorado
- Lightning: Weather alerts for Colorado
- Tornado: Is there a tornado warning now?
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Arapahoe County
What natural disasters is Arapahoe County, Colorado most at risk from?
Arapahoe County, Colorado has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 93.8 out of 100, higher than about 93% of US counties, with hail, lightning and tornadoes scoring highest of its 18 hazards and $172 million a year in expected losses.
How many federal disaster declarations has Arapahoe County had?
OpenFEMA lists 10 federal disaster declarations that included Arapahoe County since 1965, not counting 2 for COVID-19; the latest is DR-4731-CO (Severe Storms, Flooding, and Tornadoes, declared 25 August 2023). Another 12 Colorado declarations were made statewide without a county list.
How many tornadoes have hit Arapahoe County?
NOAA's Storm Prediction Center recorded 103 tornadoes touching Arapahoe County from 1950 to 2025. The deadliest: 8 Jun 1986, F2, 1.1 mi path, 0 killed, 6 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.