Frost dates for Missoula 2 NE, MT
At Missoula 2 NE, the median last spring frost (32°F) is May 10 and the median first fall frost is Oct 1, for a typical growing season of 143 days. For a 90% chance that the last frost has passed, wait until May 28. Nearby ZIP codes are in USDA hardiness zone 5b.
- May 10Last spring frost (median)50% chance of 32°F after this date
- May 28Safer planting date10% chance of 32°F after this date
- Oct 1First fall frost (median)50% chance of 32°F by this date
- 143 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 12 | Jun 1 | Jun 24 |
| 32°F | Apr 27 | May 10 | May 28 |
| 28°F | Apr 12 | Apr 28 | May 11 |
| 24°F | Mar 19 | Apr 8 | Apr 28 |
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 3 | Sep 19 | Oct 2 |
| 32°F | Sep 16 | Oct 1 | Oct 15 |
| 28°F | Sep 28 | Oct 12 | Oct 25 |
| 24°F | Oct 7 | Oct 24 | Nov 10 |
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 | 83 days | 109 days | 132 days |
| 32°F | 120 days | 143 days | 161 days |
| 28°F | 148 days | 167 days | 188 days |
| 24°F | 173 days | 198 days | 226 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 |
|---|---|---|---|
| 59802 | 5b | -15 to -10°F | 4 km |
| 59812 | 5b | -15 to -10°F | 4 km |
| 59801 | 5b | -15 to -10°F | 6 km |
| 59851 | 5b | -15 to -10°F | 8 km |
| 59803 | 5b | -15 to -10°F | 13 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 USC00245735, at 46.8983, -113.9678, elevation 1042 m (3,420 ft).
- Data quality: Representative (10+ years), 22 years of freeze data.
- Average days per year at or below 32°F: 163.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Missoula Intl Airport (10 km)
- Missoula 6 NW WFO (10 km)
- Potomac (31 km)
- Alberton (40 km)
- Stevensville (44 km)
- Saint Ignatius (47 km)
- Seeley Lake Ranger Station (49 km)
- Lindbergh Lake (60 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.