Frost dates for Byron 4north, MN
At Byron 4north, the median last spring frost (32°F) is May 12 and the median first fall frost is Sep 28, for a typical growing season of 139 days. For a 90% chance that the last frost has passed, wait until May 25. Nearby ZIP codes are in USDA hardiness zones 4b to 5a.
- May 12Last spring frost (median)50% chance of 32°F after this date
- May 25Safer planting date10% chance of 32°F after this date
- Sep 28First fall frost (median)50% chance of 32°F by this date
- 139 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 22 | Jun 4 |
| 32°F | Apr 29 | May 12 | May 25 |
| 28°F | Apr 18 | May 2 | May 15 |
| 24°F | Apr 6 | Apr 22 | May 6 |
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 5 | Sep 19 | Oct 2 |
| 32°F | Sep 14 | Sep 28 | Oct 10 |
| 28°F | Sep 22 | Oct 5 | Oct 18 |
| 24°F | Oct 2 | Oct 14 | Oct 28 |
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 | 101 days | 120 days | 138 days |
| 32°F | 118 days | 139 days | 156 days |
| 28°F | 137 days | 156 days | 175 days |
| 24°F | 156 days | 176 days | 197 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 |
|---|---|---|---|
| 55955 | 4b | -25 to -20°F | 8 km |
| 55920 | 4b | -25 to -20°F | 9 km |
| 55960 | 4b | -25 to -20°F | 10 km |
| 55963 | 4b | -25 to -20°F | 10 km |
| 55901 | 4b | -25 to -20°F | 12 km |
| 55944 | 4b | -25 to -20°F | 13 km |
| 55906 | 4b | -25 to -20°F | 19 km |
| 55927 | 4b | -25 to -20°F | 20 km |
| 55985 | 4b | -25 to -20°F | 22 km |
| 55940 | 5a | -20 to -15°F | 25 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 USC00211174, at 44.0908, -92.6400, elevation 317 m (1,041 ft).
- Data quality: Representative (10+ years), 23 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
- Zumbrota (23 km)
- Rochester Intl Airport (24 km)
- Theilman 1ssw (41 km)
- Grand Meadow (43 km)
- Owatonna (47 km)
- Austin Waste Water Plant Facility (55 km)
- Faribault (56 km)
- Red Wing Dam 3 (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.