Frost dates for Jeffrey City, WY
At Jeffrey City, the median last spring frost (32°F) is Jun 1 and the median first fall frost is Sep 13, for a typical growing season of 104 days. For a 90% chance that the last frost has passed, wait until Jun 16. Nearby ZIP codes are in USDA hardiness zone 4b.
- Jun 1Last spring frost (median)50% chance of 32°F after this date
- Jun 16Safer planting date10% chance of 32°F after this date
- Sep 13First 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 1 | Jun 15 | Jul 2 |
| 32°F | May 17 | Jun 1 | Jun 16 |
| 28°F | May 4 | May 17 | May 31 |
| 24°F | Apr 24 | May 6 | 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 | Aug 19 | Sep 3 | Sep 17 |
| 32°F | Sep 1 | Sep 13 | Sep 28 |
| 28°F | Sep 9 | Sep 24 | Oct 9 |
| 24°F | Sep 20 | Oct 5 | Oct 21 |
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 | 55 days | 79 days | 99 days |
| 32°F | 85 days | 104 days | 123 days |
| 28°F | 107 days | 129 days | 149 days |
| 24°F | 132 days | 151 days | 171 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 |
|---|---|---|---|
| 82310 | 4b | -25 to -20°F | 7 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 USC00484925, at 42.4942, -107.8292, elevation 1926 m (6,319 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 207.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Muddy Gap (35 km)
- Lander 11 SSE (72 km)
- Atlantic City (74 km)
- Riverton (74 km)
- South Pass City (80 km)
- Pathfinder Dam (80 km)
- Lander Hunt Field Airport (82 km)
- Riverton (83 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.