Frost dates / By state
Frost dates in Wisconsin
NOAA 1991–2020 normals for a 32 °F freeze. Your own yard can run a little either side.
Short answer
Across 20 NOAA weather stations in Wisconsin, the average last spring frost runs from April 19 at Milwaukee Mitchell Airport to May 26 at Rhinelander Oneida Airport. The first fall frost comes as early as September 22 at Hayward Muni Airport and as late as October 29 at Milwaukee Mitchell Airport. Planting zones near these stations run from 4a to 6a.
Wisconsin cities
- Frost dates in Milwaukee: last frost April 19, first frost October 29
- Frost dates in Madison: last frost May 1, first frost October 10
Find yours by ZIP code
The table below is by weather station. For the station nearest you, and your planting zone, type your ZIP code.
Wisconsin frost dates by weather station
| Station | Last spring frost | First fall frost | Frost-free | Zone nearby |
|---|---|---|---|---|
| Ashland Kennedy Mem Airport 826 ft | May 23 1 in 10 after June 6 | September 29 1 in 10 by September 14 | 129 days | 5a |
| Boscobel Airport 672 ft | May 3 1 in 10 after May 18 | October 7 1 in 10 by September 25 | 157 days | 5a |
| Eau Claire Rgnl Airport 885 ft | May 8 1 in 10 after May 21 | October 4 1 in 10 by September 20 | 149 days | 4b |
| Fond Du Lac Co Airport 809 ft | May 1 1 in 10 after May 17 | October 10 1 in 10 by September 27 | 162 days | 5b |
| Grantsburg 990 ft | May 11 1 in 10 after May 28 | October 1 1 in 10 by September 16 | 143 days | 4a |
| Green Bay 682 ft | April 30 1 in 10 after May 16 | October 9 1 in 10 by September 24 | 162 days | 5b |
| Hayward Muni Airport 1,204 ft | May 23 1 in 10 after June 6 | September 22 1 in 10 by September 5 | 122 days | 4a |
| Kenosha Rgnl Airport 743 ft | April 28 1 in 10 after May 13 | October 19 1 in 10 by October 1 | 174 days | 5b |
| La Crosse Muni Airport 652 ft | April 23 1 in 10 after May 6 | October 17 1 in 10 by October 3 | 177 days | 5a |
| Lone Rock Tri Co Airport 717 ft | April 30 1 in 10 after May 14 | October 9 1 in 10 by September 25 | 162 days | 5a |
| Madison Dane Rgnl Airport 866 ft | May 1 1 in 10 after May 16 | October 10 1 in 10 by September 26 | 162 days | 5b |
| Marshfield Muni Airport 1,255 ft | May 5 1 in 10 after May 20 | October 5 1 in 10 by September 21 | 153 days | 4b |
| Milwaukee Mitchell Airport 670 ft | April 19 1 in 10 after May 2 | October 29 1 in 10 by October 15 | 193 days | 6a |
| Necedah 5 WNW 933 ft | May 1 1 in 10 after May 14 | October 3 1 in 10 by September 20 | 155 days | 4b |
| Oshkosh Wittman Airport 782 ft | April 30 1 in 10 after May 13 | October 13 1 in 10 by September 29 | 166 days | 5b |
| Racine Batten Airport 674 ft | April 24 1 in 10 after May 10 | October 24 1 in 10 by October 10 | 183 days | 6a |
| Rhinelander Oneida Airport 1,599 ft | May 26 1 in 10 after June 8 | September 23 1 in 10 by September 5 | 120 days | 4b |
| Sheboygan Co Mem Airport 746 ft | May 5 1 in 10 after May 21 | October 8 1 in 10 by September 26 | 156 days | 5b |
| Wausau Dwtn Airport 1,181 ft | May 6 1 in 10 after May 21 | October 4 1 in 10 by September 21 | 151 days | 5a |
| Wisconsin Rapids Alexander Fld 1,019 ft | May 8 1 in 10 after May 22 | October 1 1 in 10 by September 19 | 146 days | 4b |
The average date is NOAA's 50% date: half of years have a later last frost, or an earlier first one. Plan by the 1-in-10 date if a freeze would cost you plants. Stations are NOAA's main weather stations, mostly airports. “Zone nearby” is the USDA 2023 zone of the nearest ZIP code within 10 miles. NOAA counts the frost season from August to July, so in the warmest places the “first fall” freeze lands after New Year.
How these dates work
Frost dates come from NOAA's 1991 to 2020 Climate Normals, which work out from each weather station's daily lows how likely the last spring freeze and the first fall freeze (32 °F) are by each date. We use the station nearest the middle of your ZIP code and show its height and distance, since a station on a hill or by a lake can differ from your yard.
The average date is the 50% date: half of years have a freeze after the spring date or before the fall one. The 1-in-10 dates are NOAA's 10% dates, the ones to plan by if a late freeze would cost you plants. Within one yard, cold air pools in low spots while walls and paving hold heat, so some corners freeze before others.
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Where the numbers come from
- USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture
- PRISM Climate Group, Oregon State University (zone data)
- NOAA NCEI, U.S. Climate Normals 1991–2020, annual/seasonal
- NOAA, Normals calculation methodology (frost-freeze probability dates)
- US Census Bureau, 2025 ZCTA gazetteer (ZIP code centers)