Delta County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Delta County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every large fire

1. Large fires mapped by the Monitoring Trends in Burn Severity program since 1984: 1,000 acres or more in the West, 500 or more in the East. Prescribed burns are excluded. Acres here are the part of each perimeter inside this place.

Monitoring Trends in Burn Severity (USGS and U.S. Forest Service), 1984 to 2026.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

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).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

Volcanoes within 100 miles

1. U.S. volcanoes within 100 miles, from the USGS Volcano Hazards Program. The threat category is the USGS 2018 National Volcanic Threat Assessment, which ranks volcanoes by how hazardous their past eruptions were and how many people and how much infrastructure lie near them. It is not a forecast of eruption.

USGS Volcano Hazards Program, retrieved October 30, 2026.

Mapped landslides

Mapped by CO GS (781), Western CO (Regmi and others, 2010) (200), NASA (3).

1. Landslides mapped in the USGS compilation of landslide inventories across the United States (version 3.0, 2025), rated probable or better. The compilation joins inventories made by federal and state agencies for different purposes and areas, so the number mapped in a county reflects how closely it has been surveyed as much as how often its slopes fail. An area with few records may simply not have been mapped. Deaths are as recorded in the inventories; a slide listed in two inventories is counted once.

USGS Landslide Inventories across the United States, version 3.0, retrieved October 27, 2026.

More event types since 1996

Costliest events since 1996

1. May 2, 2023Debris Flow$2.0 million
   National Weather Service narrative

   Excessive spring runoff and debris backing up in culverts led to a large sinkhole developing on Highway 133 north of Paonia and south of Somerset, Colorado between mile markers 14 and 19. This resulted in the closure of the highway to allow emergency repairs to be made. The sinking soils were first noticed on April 29, 2023 with the eventual collapse of the highway occurring on May 2, 2023.

2. Aug 19, 2010Thunderstorm Wind$2.0 million
   National Weather Service narrative

   A strong eastward-moving thunderstorm cell collapsed over central Delta County and produced damaging winds across portions of eastern Delta County. Measured wind speeds included 79 mph at a location 4 miles northwest of Hotchkiss and 90 mph at a location just under 3 miles southeast of Hotchkiss. The damage pach extended from about 5 miles west-northwest of Hotchkiss to about 7 miles east of Hotchkiss. The width of the damage patch extended from about 2 miles north of Hotchkiss to about just north of Crawford. Numerous trees were downed, with some trees more than 2 feet in diameter where they were snapped off. Many houses and other personal property were damaged, including the…

3. Aug 1, 2023Wildfire, West Elk And Sawatch Mountains$2.0 million
   National Weather Service narrative

   The Lowline Fire started in late July from lightning in the Gunnison National Forest, 11 miles southwest of Crested Butte, Colorado. The fire grew to 1,999 acres before it was contained in early December.

4. Jul 26, 2023Wildfire, West Elk And Sawatch Mountains$2.0 million
   National Weather Service narrative

   The Lowline Fire started in late July from lightning in the Gunnison National Forest, 11 miles southwest of Crested Butte, Colorado. The fire grew to 1,999 acres before it was contained in early December.

5. Oct 1, 2023Wildfire, West Elk And Sawatch Mountains$2.0 million
   National Weather Service narrative

   The Lowline Fire started in late July from lightning in the Gunnison National Forest, 11 miles southwest of Crested Butte, Colorado. The fire grew to 1,999 acres before it was contained in early December.

6. Sep 1, 2023Wildfire, West Elk And Sawatch Mountains$2.0 million
   National Weather Service narrative

   The Lowline Fire started in late July from lightning in the Gunnison National Forest, 11 miles southwest of Crested Butte, Colorado. The fire grew to 1,999 acres before it was contained in early December.

7. Dec 1, 2023Wildfire, West Elk And Sawatch Mountains$2.0 million
   National Weather Service narrative

   The Lowline Fire started in late July from lightning in the Gunnison National Forest, 11 miles southwest of Crested Butte, Colorado. The fire grew to 1,999 acres before it was contained in early December.

8. Nov 1, 2023Wildfire, West Elk And Sawatch Mountains$2.0 million
   National Weather Service narrative

   The Lowline Fire started in late July from lightning in the Gunnison National Forest, 11 miles southwest of Crested Butte, Colorado. The fire grew to 1,999 acres before it was contained in early December.

9. May 2, 1998Flash Flood$1.4 million
   National Weather Service narrative

   The Carl Smith Dam at Patterson Reservoir #3 failed, sending a wall of water down Leroux Creek. The earthen dam break was 200 feet wide and 45 feet high. The wall of water was up to 10 feet high and averaged 100 feet in width. Many bridges and irrigation structures were damaged or washed out. One house was flooded. Many farm and ranch buildings were destroyed or washed away. 92 lambs drowned.

10. Jun 21, 2007Wildfire, Grand And Battlement Mesas$500,000
    National Weather Service narrative

    A fire which started near the town of Mesa became wind driven in hot and dry conditions and destroyed three houses. Flames were reported to be 50 feet high with the blaze. About 30 acres were charred by the fire.

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

106°FAug 1, 1947

All-time low

−27°FFeb 13, 1905

Warmest night

73°FJul 26, 2026

Coldest day

2°FJan 13, 1963

Wettest day

1.70 inOct 20, 1963

Snowiest day

19.0 inMar 28, 1985

Hottest year

2017mean 54.6°F

Coldest year

1905mean 44.8°F

Wettest year

194116.98 in

Driest year

19004.63 in

Snowiest season

65.3 in1940-41

Station Montrose #2 (USC00055722), 5,789 ft elevation, 21.7 miles from the population centre. Daily records from 1895 to October 26, 2026; 96.2% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

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).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USC00055722.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Volcanoes USGS Volcano Hazards Program, U.S. volcanoes and 2018 threat assessment.
• Landslides USGS Landslide Inventories across the United States, version 3.0 (2025).
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.