Frost dates for Loma, MT
At Loma, the median last spring frost (32°F) is May 20 and the median first fall frost is Sep 19, for a typical growing season of 120 days. For a 90% chance that the last frost has passed, wait until Jun 3. Nearby ZIP codes are in USDA hardiness zone 4a.
- May 20Last spring frost (median)50% chance of 32°F after this date
- Jun 3Safer planting date10% chance of 32°F after this date
- Sep 19First fall frost (median)50% chance of 32°F by this date
- 120 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 20 | Jun 2 | Jun 21 |
| 32°F | May 8 | May 20 | Jun 3 |
| 28°F | Apr 25 | May 9 | May 21 |
| 24°F | Apr 10 | Apr 28 | May 9 |
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 7 | Sep 21 |
| 32°F | Sep 4 | Sep 19 | Oct 2 |
| 28°F | Sep 16 | Sep 29 | Oct 11 |
| 24°F | Sep 24 | Oct 6 | Oct 20 |
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 | 68 days | 94 days | 113 days |
| 32°F | 99 days | 120 days | 139 days |
| 28°F | 123 days | 143 days | 160 days |
| 24°F | 145 days | 162 days | 184 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 |
|---|---|---|---|
| 59460 | 4a | -30 to -25°F | 15 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 USC00245153, at 47.9364, -110.5025, elevation 786 m (2,578 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 187.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Fort Benton (17 km)
- Highwood 7 NE (35 km)
- Rudyard 19s (39 km)
- Big Sandy (40 km)
- Geraldine (41 km)
- Shonkin 7 S (45 km)
- Carter 14 W (56 km)
- Brady 27 ENE (the Knees) (58 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.