Frost dates for Bigfork 13 S, MT
At Bigfork 13 S, the median last spring frost (32°F) is May 1 and the median first fall frost is Oct 15, for a typical growing season of 165 days. For a 90% chance that the last frost has passed, wait until May 16. Nearby ZIP codes are in USDA hardiness zone 6a.
- May 1Last spring frost (median)50% chance of 32°F after this date
- May 16Safer planting date10% chance of 32°F after this date
- Oct 15First fall frost (median)50% chance of 32°F by this date
- 165 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 4 | May 16 | Jun 5 |
| 32°F | Apr 16 | May 1 | May 16 |
| 28°F | Mar 25 | Apr 11 | Apr 28 |
| 24°F | Mar 3 | Mar 23 | Apr 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 | Sep 20 | Oct 3 | Oct 15 |
| 32°F | Sep 30 | Oct 15 | Oct 30 |
| 28°F | Oct 11 | Oct 30 | Nov 18 |
| 24°F | Oct 21 | Nov 10 | Nov 30 |
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 | 114 days | 138 days | 156 days |
| 32°F | 144 days | 165 days | 186 days |
| 28°F | 174 days | 200 days | 225 days |
| 24°F | 205 days | 232 days | 261 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 |
|---|---|---|---|
| 59931 | 6a | -10 to -5°F | 17 km |
| 59922 | 6a | -10 to -5°F | 20 km |
| 59914 | 6a | -10 to -5°F | 20 km |
| 59929 | 6a | -10 to -5°F | 28 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 USC00240755, at 47.8769, -114.0336, elevation 908 m (2,979 ft).
- Data quality: Representative (10+ years), 24 years of freeze data.
- Average days per year at or below 32°F: 127.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Swan Lake (15 km)
- Polson (25 km)
- Skq Dam (27 km)
- Creston (35 km)
- Kalispell Glacier Airport (50 km)
- Hungry Horse Dam (52 km)
- Lindbergh Lake (57 km)
- Saint Ignatius (63 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.