Frost dates for Grant, CO
At Grant, the median last spring frost (32°F) is Jun 15 and the median first fall frost is Sep 9, for a typical growing season of 84 days. For a 90% chance that the last frost has passed, wait until Jun 30. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- Jun 15Last spring frost (median)50% chance of 32°F after this date
- Jun 30Safer planting date10% chance of 32°F after this date
- Sep 9First fall frost (median)50% chance of 32°F by this date
- 84 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 |
|---|---|---|---|
| 32°F | Jun 1 | Jun 15 | Jun 30 |
| 28°F | May 16 | May 30 | Jun 12 |
| 24°F | May 2 | May 14 | May 27 |
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 |
|---|---|---|---|
| 32°F | Aug 26 | Sep 9 | Sep 22 |
| 28°F | Sep 9 | Sep 22 | Oct 4 |
| 24°F | Sep 17 | Oct 1 | Oct 16 |
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 | 32 days | 53 days | 72 days |
| 32°F | 65 days | 84 days | 104 days |
| 28°F | 95 days | 116 days | 134 days |
| 24°F | 120 days | 140 days | 158 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 |
|---|---|---|---|
| 80475 | 5b | -15 to -10°F | 8 km |
| 80448 | 5b | -15 to -10°F | 14 km |
| 80456 | 5a | -20 to -15°F | 17 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 USC00053530, at 39.4608, -105.6786, elevation 2644 m (8,675 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 236.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Bailey (18 km)
- Cabin Creek (22 km)
- Georgetown (27 km)
- Dillon 1 E (36 km)
- Evergreen (37 km)
- Fairplay S Park Rd (38 km)
- Cheesman (44 km)
- Climax (45 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.