Montana · NOAA station USC00240111
Frost dates for Alder 19s, MT
Alder 19s can freeze in any month: NOAA flags it as having a year-round risk of 32°F, too cold to compute spring and fall frost dates. The median stretch between 32°F freezes is 77 days. Nearby ZIP codes are in USDA hardiness zone 5a.
- 100%Chance of 32°F in a year
- 77 daysMedian freeze-free stretch
- 219Days at or below 32°Faverage per year
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 |
|---|---|---|---|
| 59710 | 5a | -20 to -15°F | 5 km |
| 59755 | 5a | -20 to -15°F | 22 km |
| 59749 | 5a | -20 to -15°F | 40 km |
| 59729 | 5a | -20 to -15°F | 42 km |
| 59720 | 5a | -20 to -15°F | 43 km |
| 59739 | 5a | -20 to -15°F | 49 km |
| 59740 | 5a | -20 to -15°F | 50 km |
| 59754 | 5a | -20 to -15°F | 52 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 USC00240111, at 45.0961, -112.0856, elevation 1752 m (5,749 ft).
- Data quality: Representative (10+ years), 11 years of freeze data.
- Average days per year at or below 32°F: 219.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Alder 17 S (4 km)
- Virginia City (24 km)
- Laurin 2ne (30 km)
- Ennis (40 km)
- Dillon Airport (41 km)
- Dillon U Of Montana Western (45 km)
- Twin Bridges (54 km)
- Norris Madison Power House (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.