Frost dates for Grantsburg, WI
At Grantsburg, the median last spring frost (32°F) is May 11 and the median first fall frost is Oct 1, for a typical growing season of 141 days. For a 90% chance that the last frost has passed, wait until May 28. Nearby ZIP codes are in USDA hardiness zones 4a to 4b.
- May 11Last 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
- 141 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 23 | Jun 6 |
| 32°F | Apr 27 | May 11 | May 28 |
| 28°F | Apr 15 | Apr 30 | May 17 |
| 24°F | Apr 5 | Apr 19 | May 4 |
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 22 | Oct 5 |
| 32°F | Sep 16 | Oct 1 | Oct 14 |
| 28°F | Sep 26 | Oct 11 | Oct 26 |
| 24°F | Oct 6 | Oct 22 | Nov 7 |
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 | 97 days | 120 days | 142 days |
| 32°F | 117 days | 141 days | 160 days |
| 28°F | 140 days | 161 days | 182 days |
| 24°F | 162 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% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 54840 | 4a | -30 to -25°F | 2 km |
| 55063 | 4a | -30 to -25°F | 18 km |
| 54872 | 4b | -25 to -20°F | 23 km |
| 55069 | 4b | -25 to -20°F | 23 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 USW00014995, at 45.7728, -92.6886, elevation 302 m (990 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 177.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Luck (27 km)
- Danbury (36 km)
- St. Croix Falls (40 km)
- Cumberland (58 km)
- Amery (58 km)
- Spooner Ag Reservoir Station (63 km)
- Minong 5 WSW (71 km)
- Rice Lake (82 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.