Frost dates for Koosharem, UT
At Koosharem, the median last spring frost (32°F) is Jun 6 and the median first fall frost is Sep 21, for a typical growing season of 104 days. For a 90% chance that the last frost has passed, wait until Jun 26. Nearby ZIP codes are in USDA hardiness zones 5b to 6a.
- Jun 6Last spring frost (median)50% chance of 32°F after this date
- Jun 26Safer planting date10% chance of 32°F after this date
- Sep 21First fall frost (median)50% chance of 32°F by this date
- 104 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 5 | Jun 22 | Jul 11 |
| 32°F | May 24 | Jun 6 | Jun 26 |
| 28°F | May 7 | May 26 | Jun 10 |
| 24°F | Apr 22 | May 9 | May 29 |
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 26 | Sep 10 | Sep 23 |
| 32°F | Sep 5 | Sep 21 | Oct 2 |
| 28°F | Sep 14 | Sep 29 | Oct 12 |
| 24°F | Sep 25 | Oct 8 | Oct 24 |
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 | 54 days | 79 days | 99 days |
| 32°F | 81 days | 104 days | 123 days |
| 28°F | 104 days | 126 days | 148 days |
| 24°F | 128 days | 152 days | 174 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 |
|---|---|---|---|
| 84732 | 5b | -15 to -10°F | 7 km |
| 84701 | 6a | -10 to -5°F | 12 km |
| 84744 | 6a | -10 to -5°F | 13 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 USC00424764, at 38.5086, -111.8842, elevation 2112 m (6,930 ft).
- Data quality: Representative (10+ years), 14 years of freeze data.
- Average days per year at or below 32°F: 221.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Loa (24 km)
- Angle (30 km)
- Marysvale (30 km)
- Richfield Radio Ksvc (33 km)
- Fremont Indian State Park (40 km)
- Circleville (51 km)
- Torrey 7 E (56 km)
- Kanosh (58 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.