Frost dates for Platteville, WI
At Platteville, the median last spring frost (32°F) is Apr 30 and the median first fall frost is Oct 13, for a typical growing season of 166 days. For a 90% chance that the last frost has passed, wait until May 13. Nearby ZIP codes are in USDA hardiness zone 5a.
- Apr 30Last spring frost (median)50% chance of 32°F after this date
- May 13Safer planting date10% chance of 32°F after this date
- Oct 13First fall frost (median)50% chance of 32°F by this date
- 166 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 25 | May 8 | May 23 |
| 32°F | Apr 14 | Apr 30 | May 13 |
| 28°F | Apr 3 | Apr 17 | May 2 |
| 24°F | Mar 21 | Apr 6 | Apr 21 |
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 20 | Oct 3 | Oct 14 |
| 32°F | Sep 29 | Oct 13 | Oct 24 |
| 28°F | Oct 9 | Oct 22 | Nov 3 |
| 24°F | Oct 20 | 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 | 129 days | 146 days | 165 days |
| 32°F | 146 days | 166 days | 185 days |
| 28°F | 167 days | 187 days | 206 days |
| 24°F | 190 days | 209 days | 232 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 |
|---|---|---|---|
| 53818 | 5a | -20 to -15°F | 2 km |
| 53510 | 5a | -20 to -15°F | 12 km |
| 53580 | 5a | -20 to -15°F | 14 km |
| 53807 | 5a | -20 to -15°F | 15 km |
| 53554 | 5a | -20 to -15°F | 18 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 USC00476646, at 42.7489, -90.4656, elevation 302 m (990 ft).
- Data quality: Representative (10+ years), 19 years of freeze data.
- Average days per year at or below 32°F: 154.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Lancaster 4 WSW (28 km)
- Darlington Wastewater Plant (30 km)
- Dodgeville Wastewater Plant (37 km)
- Boscobel Airport (48 km)
- Steuben 4 SE (52 km)
- Lone Rock Tri Co Airport (56 km)
- Prairie Du Chien (64 km)
- Richland Center (65 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.