Frost dates for Colony, WY
At Colony, the median last spring frost (32°F) is May 7 and the median first fall frost is Oct 3, for a typical growing season of 149 days. For a 90% chance that the last frost has passed, wait until May 21. Nearby ZIP codes are in USDA hardiness zones 4b to 5b.
- May 7Last spring frost (median)50% chance of 32°F after this date
- May 21Safer planting date10% chance of 32°F after this date
- Oct 3First fall frost (median)50% chance of 32°F by this date
- 149 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 6 | May 17 | May 31 |
| 32°F | Apr 26 | May 7 | May 21 |
| 28°F | Apr 13 | Apr 28 | May 12 |
| 24°F | Apr 2 | Apr 16 | May 1 |
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 11 | Sep 25 | Oct 7 |
| 32°F | Sep 19 | Oct 3 | Oct 18 |
| 28°F | Sep 29 | Oct 13 | Oct 27 |
| 24°F | Oct 5 | Oct 22 | Nov 6 |
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 | 110 days | 130 days | 147 days |
| 32°F | 129 days | 149 days | 166 days |
| 28°F | 147 days | 167 days | 188 days |
| 24°F | 167 days | 188 days | 209 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 57717 | 4b | -25 to -20°F | 21 km |
| 82710 | 5a | -20 to -15°F | 23 km |
| 82711 | 5a | -20 to -15°F | 31 km |
| 82712 | 5a | -20 to -15°F | 38 km |
| 82720 | 4b | -25 to -20°F | 42 km |
| 57762 | 4b | -25 to -20°F | 44 km |
| 59311 | 4b | -25 to -20°F | 45 km |
| 57779 | 5b | -15 to -10°F | 46 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 USC00481905, at 44.8711, -104.1533, elevation 1061 m (3,480 ft).
- Data quality: Representative (10+ years), 16 years of freeze data.
- Average days per year at or below 32°F: 160.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Hulett (41 km)
- Sundance 8 NNW (45 km)
- Sundance (54 km)
- Devils Twr #2 (55 km)
- Upton (94 km)
- Weston 1 E (94 km)
- Moorcroft 3s (95 km)
- Newcastle (114 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.