Frost dates for Sullivan 3se, WI
At Sullivan 3se, the median last spring frost (32°F) is May 3 and the median first fall frost is Oct 9, for a typical growing season of 157 days. For a 90% chance that the last frost has passed, wait until May 21. Nearby ZIP codes are in USDA hardiness zone 5b.
- May 3Last spring frost (median)50% chance of 32°F after this date
- May 21Safer planting date10% chance of 32°F after this date
- Oct 9First fall frost (median)50% chance of 32°F by this date
- 157 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 | Apr 30 | May 16 | May 30 |
| 32°F | Apr 18 | May 3 | May 21 |
| 28°F | Apr 7 | Apr 22 | May 7 |
| 24°F | Mar 27 | Apr 10 | Apr 28 |
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 17 | Sep 29 | Oct 13 |
| 32°F | Sep 25 | Oct 9 | Oct 25 |
| 28°F | Oct 4 | Oct 22 | Nov 5 |
| 24°F | Oct 19 | Nov 1 | Nov 16 |
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 | 117 days | 137 days | 157 days |
| 32°F | 135 days | 157 days | 179 days |
| 28°F | 159 days | 181 days | 202 days |
| 24°F | 183 days | 204 days | 226 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 |
|---|---|---|---|
| 53118 | 5b | -15 to -10°F | 5 km |
| 53178 | 5b | -15 to -10°F | 8 km |
| 53156 | 5b | -15 to -10°F | 9 km |
| 53119 | 5b | -15 to -10°F | 10 km |
| 53137 | 5b | -15 to -10°F | 11 km |
| 53153 | 5b | -15 to -10°F | 12 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 USC00478316, at 42.9675, -88.5497, elevation 284 m (933 ft).
- Data quality: Representative (10+ years), 25 years of freeze data.
- Average days per year at or below 32°F: 148.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Oconomowoc Wastewater Plant (15 km)
- Whitewater (19 km)
- Jefferson Wastewater Plant (21 km)
- Waukesha Wastewater Plant (25 km)
- Fort Atkinson (26 km)
- Watertown Wastewater Plant (28 km)
- Lake Mills Wastewater Plant (31 km)
- Brookfield Wastewater Plant (32 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.