Frost dates for Malta 7 E, MT
At Malta 7 E, the median last spring frost (32°F) is May 7 and the median first fall frost is Sep 28, for a typical growing season of 143 days. For a 90% chance that the last frost has passed, wait until May 21. Nearby ZIP codes are in USDA hardiness zones 3b to 4a.
- May 7Last spring frost (median)50% chance of 32°F after this date
- May 21Safer planting date10% chance of 32°F after this date
- Sep 28First 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 7 | May 18 | Jun 1 |
| 32°F | Apr 24 | May 7 | May 21 |
| 28°F | Apr 11 | Apr 26 | May 8 |
| 24°F | Mar 29 | Apr 15 | 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 2 | Sep 19 | Oct 1 |
| 32°F | Sep 14 | Sep 28 | Oct 11 |
| 28°F | Sep 24 | Oct 8 | Oct 22 |
| 24°F | Oct 1 | Oct 18 | Nov 1 |
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 | 99 days | 121 days | 138 days |
| 32°F | 122 days | 143 days | 161 days |
| 28°F | 144 days | 164 days | 185 days |
| 24°F | 161 days | 185 days | 207 days |
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 |
|---|---|---|---|
| 59261 | 3b | -35 to -30°F | 27 km |
| 59538 | 4a | -30 to -25°F | 42 km |
| 59544 | 3b | -35 to -30°F | 47 km |
| 59241 | 3b | -35 to -30°F | 51 km |
| 59537 | 3b | -35 to -30°F | 53 km |
| 59524 | 4a | -30 to -25°F | 57 km |
| 59273 | 4a | -30 to -25°F | 59 km |
| 59542 | 4a | -30 to -25°F | 65 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 USC00245338, at 48.3939, -107.7286, elevation 680 m (2,231 ft).
- Data quality: Representative (10+ years), 23 years of freeze data.
- Average days per year at or below 32°F: 186.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Malta (11 km)
- Saco 1 NNW (29 km)
- Content 4 NNE (38 km)
- Hinsdale 4 SW (43 km)
- Malta 35 S (64 km)
- Port Of Morgan (68 km)
- Harlem 20s (72 km)
- Fort Belknap 2 SW (78 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.