Frost dates for Bozeman 6 W Exp. Farm, MT
At Bozeman 6 W Exp. Farm, the median last spring frost (32°F) is May 23 and the median first fall frost is Sep 23, for a typical growing season of 123 days. For a 90% chance that the last frost has passed, wait until Jun 12. Nearby ZIP codes are in USDA hardiness zone 5a.
- May 23Last spring frost (median)50% chance of 32°F after this date
- Jun 12Safer planting date10% chance of 32°F after this date
- Sep 23First fall frost (median)50% chance of 32°F by this date
- 123 daysGrowing season (median)between 32°F freezes
USDA hardiness zone 5a (-20 to -15°F) · see all zone 5a frost dates
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 26 | Jun 13 | Jun 30 |
| 32°F | May 5 | May 23 | Jun 12 |
| 28°F | Apr 20 | May 2 | May 18 |
| 24°F | Apr 4 | Apr 21 | May 6 |
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 22 | Sep 9 | Sep 24 |
| 32°F | Sep 4 | Sep 23 | Oct 6 |
| 28°F | Sep 17 | Oct 3 | Oct 19 |
| 24°F | Sep 29 | Oct 16 | Nov 1 |
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 | 63 days | 87 days | 111 days |
| 32°F | 96 days | 123 days | 144 days |
| 28°F | 131 days | 153 days | 171 days |
| 24°F | 154 days | 175 days | 199 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 |
|---|---|---|---|
| 59718 | 5a | -20 to -15°F | 4 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 USC00241047, at 45.6728, -111.1547, elevation 1455 m (4,775 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 180.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Bozeman Montana State Univ (8 km)
- Bozeman Gallatin Field (13 km)
- Logan Landfill (30 km)
- Trident (39 km)
- Norris Madison Power House (43 km)
- Big Sky 2WNW (46 km)
- Livingston 12 S (50 km)
- Wilsall 1S (52 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.