Montana · NOAA station USW00004137
Frost dates for Dillon 18 WSW, MT
Dillon 18 WSW 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 72 days. Nearby ZIP codes are in USDA hardiness zone 5a.
- 100%Chance of 32°F in a year
- 72 daysMedian freeze-free stretch
- 230Days 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% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 59725 | 5a | -20 to -15°F | 16 km |
| 59746 | 5a | -20 to -15°F | 26 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 USW00004137, at 45.1581, -113.0058, elevation 1820 m (5,971 ft).
- Data quality: Representative (10+ years), 13 years of freeze data.
- Average days per year at or below 32°F: 230.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Dillon U Of Montana Western (29 km)
- Dillon Airport (37 km)
- Jackson (39 km)
- Glen 4 N (47 km)
- Wisdom (62 km)
- Lima (67 km)
- Twin Bridges (69 km)
- Divide (69 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.