Frost dates for Altamont, UT
At Altamont, the median last spring frost (32°F) is May 31 and the median first fall frost is Sep 23, for a typical growing season of 112 days. For a 90% chance that the last frost has passed, wait until Jun 16. Nearby ZIP codes are in USDA hardiness zones 5b to 6a.
- May 31Last spring frost (median)50% chance of 32°F after this date
- Jun 16Safer planting date10% chance of 32°F after this date
- Sep 23First fall frost (median)50% chance of 32°F by this date
- 112 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 30 | Jun 13 | Jun 29 |
| 32°F | May 16 | May 31 | Jun 16 |
| 28°F | May 1 | May 17 | Jun 4 |
| 24°F | Apr 19 | May 2 | May 19 |
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 26 |
| 32°F | Sep 6 | Sep 23 | Oct 5 |
| 28°F | Sep 17 | Oct 1 | Oct 16 |
| 24°F | Sep 29 | Oct 13 | Oct 28 |
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 | 70 days | 91 days | 111 days |
| 32°F | 90 days | 112 days | 133 days |
| 28°F | 113 days | 136 days | 158 days |
| 24°F | 140 days | 162 days | 182 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 |
|---|---|---|---|
| 84001 | 5b | -15 to -10°F | 3 km |
| 84002 | 6a | -10 to -5°F | 7 km |
| 84007 | 5b | -15 to -10°F | 8 km |
| 84073 | 6a | -10 to -5°F | 10 km |
| 84051 | 6a | -10 to -5°F | 11 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 USC00420074, at 40.3669, -110.2986, elevation 1968 m (6,456 ft).
- Data quality: Representative (10+ years), 25 years of freeze data.
- Average days per year at or below 32°F: 194.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Neola (22 km)
- Duchesne (23 km)
- Moon Lake (27 km)
- Myton (28 km)
- Roosevelt Radio (30 km)
- Fort Duchesne (38 km)
- Maeser 9nw (58 km)
- Ouray 4ne (61 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.