Frost dates for Altenbern, CO
At Altenbern, the median last spring frost (32°F) is May 25 and the median first fall frost is Sep 25, for a typical growing season of 120 days. For a 90% chance that the last frost has passed, wait until Jun 13. Nearby ZIP codes are in USDA hardiness zones 6a to 6b.
- May 25Last spring frost (median)50% chance of 32°F after this date
- Jun 13Safer planting date10% chance of 32°F after this date
- Sep 25First fall frost (median)50% chance of 32°F by this date
- 120 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 | May 24 | Jun 8 | Jun 27 |
| 32°F | May 10 | May 25 | Jun 13 |
| 28°F | Apr 24 | May 8 | May 29 |
| 24°F | Apr 8 | Apr 24 | May 11 |
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 | Sep 1 | Sep 15 | Sep 29 |
| 32°F | Sep 10 | Sep 25 | Oct 8 |
| 28°F | Sep 21 | Oct 4 | Oct 19 |
| 24°F | Sep 29 | Oct 16 | Nov 1 |
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 | 74 days | 97 days | 117 days |
| 32°F | 98 days | 120 days | 143 days |
| 28°F | 124 days | 148 days | 167 days |
| 24°F | 151 days | 173 days | 195 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 |
|---|---|---|---|
| 81630 | 6b | -5 to 0°F | 16 km |
| 81635 | 6a | -10 to -5°F | 27 km |
| 81650 | 6a | -10 to -5°F | 36 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 USC00050214, at 39.4992, -108.3808, elevation 1718 m (5,637 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 189.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Grand Junction Walker Field (43 km)
- Palisade (43 km)
- Grand Junction WFO (44 km)
- Collbran 1wsw (45 km)
- Fruita (49 km)
- Grand Junction 6ese (51 km)
- Colorado National Monument (54 km)
- Rifle Garfield Co Airport (56 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.