Frost dates for Milwaukee Mitchell Airport, WI
At Milwaukee Mitchell Airport, the median last spring frost (32°F) is Apr 19 and the median first fall frost is Oct 29, for a typical growing season of 192 days. For a 90% chance that the last frost has passed, wait until May 2. Nearby ZIP codes are in USDA hardiness zone 6a.
- Apr 19Last spring frost (median)50% chance of 32°F after this date
- May 2Safer planting date10% chance of 32°F after this date
- Oct 29First fall frost (median)50% chance of 32°F by this date
- 192 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 18 | May 1 | May 15 |
| 32°F | Apr 6 | Apr 19 | May 2 |
| 28°F | Mar 24 | Apr 6 | Apr 20 |
| 24°F | Mar 11 | Mar 28 | Apr 9 |
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 | Oct 5 | Oct 18 | Oct 30 |
| 32°F | Oct 15 | Oct 29 | Nov 10 |
| 28°F | Oct 27 | Nov 8 | Nov 22 |
| 24°F | Nov 3 | Nov 17 | Dec 1 |
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 | 150 days | 168 days | 188 days |
| 32°F | 173 days | 192 days | 211 days |
| 28°F | 197 days | 215 days | 235 days |
| 24°F | 215 days | 234 days | 255 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 |
|---|---|---|---|
| 53207 | 6a | -10 to -5°F | 2 km |
| 53221 | 6a | -10 to -5°F | 3 km |
| 53110 | 6a | -10 to -5°F | 4 km |
| 53235 | 6a | -10 to -5°F | 4 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 USW00014839, at 42.9550, -87.9044, elevation 204 m (670 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 123.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- South Milwaukee Wastewater Plant (7 km)
- Hales Corners/whitnall Park/bo (10 km)
- West Allis (11 km)
- Mount Mary College (17 km)
- Racine Batten Airport (23 km)
- Brookfield Wastewater Plant (25 km)
- Waukesha Wastewater Plant (29 km)
- Racine (30 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.