Frost dates for Coal Creek Canyon, CO
At Coal Creek Canyon, the median last spring frost (32°F) is Jun 5 and the median first fall frost is Sep 16, for a typical growing season of 103 days. For a 90% chance that the last frost has passed, wait until Jun 19. Nearby ZIP codes are in USDA hardiness zone 5b.
- Jun 5Last spring frost (median)50% chance of 32°F after this date
- Jun 19Safer planting date10% chance of 32°F after this date
- Sep 16First fall frost (median)50% chance of 32°F by this date
- 103 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Jun 4 | Jun 19 | Jul 3 |
| 32°F | May 23 | Jun 5 | Jun 19 |
| 28°F | May 7 | May 21 | Jun 5 |
| 24°F | Apr 28 | May 9 | May 22 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Aug 18 | Sep 4 | Sep 17 |
| 32°F | Sep 2 | Sep 16 | Sep 28 |
| 28°F | Sep 11 | Sep 26 | Oct 10 |
| 24°F | Sep 21 | Oct 5 | Oct 20 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 53 days | 76 days | 97 days |
| 32°F | 83 days | 103 days | 122 days |
| 28°F | 104 days | 126 days | 144 days |
| 24°F | 125 days | 147 days | 167 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 80471 | 5b | -15 to -10°F | 5 km |
| 80422 | 5b | -15 to -10°F | 14 km |
| 80427 | 5b | -15 to -10°F | 16 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00051681, at 39.8958, -105.3847, elevation 2728 m (8,950 ft).
- Data quality: Standard (24+ years of data), 25 years of freeze data.
- Average days per year at or below 32°F: 211.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Gross Rsvr (5 km)
- Boulder (15 km)
- Ralston Rsvr (15 km)
- Boulder 14 W (20 km)
- Wheat Ridge 2 (27 km)
- Lakewood (28 km)
- Evergreen (29 km)
- Northglenn (32 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.