Montana · NOAA station USC00241557
Frost dates for Cascade 20 SSE, MT
Cascade 20 SSE 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 70 days. Nearby ZIP codes are in USDA hardiness zones 4a to 5a.
- 100%Chance of 32°F in a year
- 70 daysMedian freeze-free stretch
- 197Days 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 |
|---|---|---|---|
| 59421 | 4b | -25 to -20°F | 12 km |
| 59405 | 4b | -25 to -20°F | 39 km |
| 59602 | 4b | -25 to -20°F | 39 km |
| 59480 | 4b | -25 to -20°F | 45 km |
| 59472 | 4b | -25 to -20°F | 47 km |
| 59485 | 4a | -30 to -25°F | 49 km |
| 59648 | 4b | -25 to -20°F | 49 km |
| 59635 | 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 USC00241557, at 46.9956, -111.5772, elevation 1402 m (4,600 ft).
- Data quality: Representative (10+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 197.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Adel (8 km)
- Cascade 5 S (27 km)
- Holter Dam (33 km)
- Millegan 14 SE (34 km)
- Helena Regional Airport (52 km)
- Great Falls WFO (54 km)
- Sun River 4 S (55 km)
- Great Falls Intl Airport (55 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.