Frost dates for Isle 12n, MN
At Isle 12n, the median last spring frost (32°F) is May 10 and the median first fall frost is Oct 3, for a typical growing season of 144 days. For a 90% chance that the last frost has passed, wait until May 28. Nearby ZIP codes are in USDA hardiness zone 4a.
- 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 3First fall frost (median)50% chance of 32°F by this date
- 144 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 24 | Jun 7 |
| 32°F | Apr 27 | May 10 | May 28 |
| 28°F | Apr 15 | Apr 30 | May 12 |
| 24°F | Apr 5 | Apr 19 | May 2 |
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 7 | Sep 24 | Oct 7 |
| 32°F | Sep 19 | Oct 3 | Oct 17 |
| 28°F | Oct 1 | Oct 16 | Oct 31 |
| 24°F | Oct 10 | Oct 27 | 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 | 99 days | 121 days | 143 days |
| 32°F | 124 days | 144 days | 164 days |
| 28°F | 147 days | 166 days | 187 days |
| 24°F | 169 days | 189 days | 209 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 |
|---|---|---|---|
| 56342 | 4a | -30 to -25°F | 18 km |
| 56350 | 4a | -30 to -25°F | 21 km |
| 56386 | 4a | -30 to -25°F | 23 km |
| 56359 | 4a | -30 to -25°F | 28 km |
| 56450 | 4a | -30 to -25°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 USC00214103, at 46.3197, -93.5014, elevation 392 m (1,285 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 176.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Aitkin 2e (26 km)
- Sandstone 6 W (45 km)
- Brainerd Crow Wing Co Airport (49 km)
- Mora (51 km)
- Hinckley (54 km)
- Brainerd (54 km)
- Sandy Lake Dam Libby (55 km)
- Wright 3 E (58 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.