Frost dates for Highwood 7 NE, MT
At Highwood 7 NE, the median last spring frost (32°F) is May 7 and the median first fall frost is Oct 2, for a typical growing season of 149 days. For a 90% chance that the last frost has passed, wait until May 21. Nearby ZIP codes are in USDA hardiness zone 4b.
- May 7Last spring frost (median)50% chance of 32°F after this date
- May 21Safer planting date10% chance of 32°F after this date
- Oct 2First fall frost (median)50% chance of 32°F by this date
- 149 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 8 | May 21 | Jun 3 |
| 32°F | Apr 24 | May 7 | May 21 |
| 28°F | Apr 5 | Apr 24 | May 8 |
| 24°F | Mar 22 | Apr 11 | Apr 30 |
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 | Sep 10 | Sep 24 | Oct 5 |
| 32°F | Sep 19 | Oct 2 | Oct 19 |
| 28°F | Sep 29 | Oct 15 | Nov 1 |
| 24°F | Oct 4 | Oct 25 | Nov 11 |
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 | 105 days | 124 days | 143 days |
| 32°F | 129 days | 149 days | 168 days |
| 28°F | 152 days | 174 days | 198 days |
| 24°F | 167 days | 194 days | 220 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 |
|---|---|---|---|
| 59450 | 4b | -25 to -20°F | 11 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 USC00244133, at 47.6414, -110.6678, elevation 1097 m (3,600 ft).
- Data quality: Estimated from nearby stations (2+ years), 8 years of freeze data.
- Average days per year at or below 32°F: 141.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Shonkin 7 S (14 km)
- Fort Benton (21 km)
- Geraldine (30 km)
- Loma (35 km)
- Raynesford 2 NNW (39 km)
- Carter 14 W (45 km)
- Great Falls 16st (49 km)
- Great Falls Intl Airport (57 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.