Frost dates for Bayfield Fish Hatchery, WI
At Bayfield Fish Hatchery, the median last spring frost (32°F) is May 23 and the median first fall frost is Oct 2, for a typical growing season of 131 days. For a 90% chance that the last frost has passed, wait until Jun 5. Nearby ZIP codes are in USDA hardiness zone 4b.
- May 23Last spring frost (median)50% chance of 32°F after this date
- Jun 5Safer planting date10% chance of 32°F after this date
- Oct 2First fall frost (median)50% chance of 32°F by this date
- 131 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 22 | Jun 3 | Jun 17 |
| 32°F | May 8 | May 23 | Jun 5 |
| 28°F | Apr 23 | May 9 | May 25 |
| 24°F | Apr 10 | Apr 28 | May 15 |
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 17 | Oct 2 | Oct 16 |
| 28°F | Sep 30 | Oct 14 | Oct 29 |
| 24°F | Oct 10 | Oct 28 | Nov 13 |
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 | 91 days | 110 days | 127 days |
| 32°F | 112 days | 131 days | 153 days |
| 28°F | 134 days | 155 days | 180 days |
| 24°F | 160 days | 183 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 |
|---|---|---|---|
| 54891 | 4b | -25 to -20°F | 13 km |
| 54827 | 4b | -25 to -20°F | 19 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 USC00470604, at 46.7872, -90.8642, elevation 188 m (615 ft).
- Data quality: Estimated from nearby stations (2+ years), 5 years of freeze data.
- Average days per year at or below 32°F: 185.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Madeline Island (8 km)
- Bayfield 6 N (11 km)
- Ashland 3s (26 km)
- Ashland Kennedy Mem Airport (27 km)
- Port Wing (40 km)
- Saxon 1wsw (47 km)
- Mellen 4 NE (50 km)
- Drummond (59 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.