Frost dates for Afton, WY
At Afton, the median last spring frost (32°F) is Jun 20 and the median first fall frost is Sep 1, for a typical growing season of 71 days. For a 90% chance that the last frost has passed, wait until Jul 7. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- Jun 20Last spring frost (median)50% chance of 32°F after this date
- Jul 7Safer planting date10% chance of 32°F after this date
- Sep 1First fall frost (median)50% chance of 32°F by this date
- 71 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 2 | Jun 20 | Jul 7 |
| 28°F | May 10 | Jun 1 | Jun 20 |
| 24°F | Apr 24 | May 9 | May 30 |
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 12 | Sep 1 | Sep 15 |
| 28°F | Aug 29 | Sep 13 | Sep 27 |
| 24°F | Sep 12 | Sep 27 | Oct 12 |
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 | 24 days | 42 days | 65 days |
| 32°F | 49 days | 71 days | 93 days |
| 28°F | 77 days | 104 days | 128 days |
| 24°F | 112 days | 137 days | 160 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 |
|---|---|---|---|
| 83110 | 5b | -15 to -10°F | 6 km |
| 83119 | 5a | -20 to -15°F | 11 km |
| 83126 | 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 USC00480027, at 42.7331, -110.9217, elevation 1904 m (6,248 ft).
- Data quality: Representative (10+ years), 16 years of freeze data.
- Average days per year at or below 32°F: 227.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Bedford 3 SE (16 km)
- Bondurant (68 km)
- Daniel Fish Hatchery (68 km)
- Big Piney Marbleton Airport (69 km)
- La Barge (79 km)
- Cora (80 km)
- Jackson (85 km)
- Pinedale (88 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.