Frost dates for Moorcroft 3s, WY
At Moorcroft 3s, the median last spring frost (32°F) is May 22 and the median first fall frost is Sep 28, for a typical growing season of 127 days. For a 90% chance that the last frost has passed, wait until Jun 9. Nearby ZIP codes are in USDA hardiness zones 4b to 5a.
- May 22Last spring frost (median)50% chance of 32°F after this date
- Jun 9Safer planting date10% chance of 32°F after this date
- Sep 28First fall frost (median)50% chance of 32°F by this date
- 127 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 18 | Jun 1 | Jun 28 |
| 32°F | May 8 | May 22 | Jun 9 |
| 28°F | Apr 27 | May 10 | May 27 |
| 24°F | Apr 12 | Apr 29 | May 14 |
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 16 | Oct 1 |
| 32°F | Sep 11 | Sep 28 | Oct 10 |
| 28°F | Sep 21 | Oct 5 | Oct 20 |
| 24°F | Sep 30 | Oct 16 | Oct 29 |
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 | 77 days | 105 days | 127 days |
| 32°F | 102 days | 127 days | 148 days |
| 28°F | 125 days | 149 days | 167 days |
| 24°F | 146 days | 168 days | 190 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 |
|---|---|---|---|
| 82727 | 4b | -25 to -20°F | 25 km |
| 82730 | 4b | -25 to -20°F | 26 km |
| 82721 | 4b | -25 to -20°F | 27 km |
| 82714 | 4b | -25 to -20°F | 42 km |
| 82723 | 4b | -25 to -20°F | 47 km |
| 82729 | 4b | -25 to -20°F | 48 km |
| 82718 | 5a | -20 to -15°F | 63 km |
| 82711 | 5a | -20 to -15°F | 66 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 USW00024088, at 44.2169, -104.9292, elevation 1318 m (4,325 ft).
- Data quality: Representative (10+ years), 13 years of freeze data.
- Average days per year at or below 32°F: 196.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Dillinger (20 km)
- Upton (29 km)
- Gillette 4se (42 km)
- Devils Twr #2 (44 km)
- Sundance (50 km)
- Gillette Campbell Airport (51 km)
- Sundance 8 NNW (51 km)
- Weston 1 E (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.