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Wisconsin frost dates
Across the 20Wisconsin weather stations below, the average last spring frost ranges from Apr 19 in Milwaukee Mitchell to May 26 in Rhinelander Oneida. The statewide middle is about May 2 for the last spring frost and Oct 7 for the first fall frost. Milwaukee Mitchell has the longest growing season, about 193 days. Hardiness zones in these places: 4a, 4b, 5a, 5b, 6a.
Frost dates by city
| Place | Zone | Last spring frost | 90% safe after | First fall frost | Frost-free days |
|---|---|---|---|---|---|
| Milwaukee Mitchell | 6a | Apr 19 | May 2 | Oct 29 | 193 |
| La Crosse | 5a | Apr 23 | May 6 | Oct 17 | 177 |
| Racine Batten | 6a | Apr 24 | May 10 | Oct 24 | 183 |
| Kenosha | 5b | Apr 28 | May 13 | Oct 19 | 174 |
| Green Bay | 5b | Apr 30 | May 16 | Oct 9 | 162 |
| Lone Rock Tri | 5a | Apr 30 | May 14 | Oct 9 | 162 |
| Oshkosh Wittman | 5b | Apr 30 | May 13 | Oct 13 | 166 |
| Fond Du Lac | 5b | May 1 | May 17 | Oct 10 | 162 |
| Madison Dane | 5b | May 1 | May 16 | Oct 10 | 162 |
| Necedah 5 Wnw | 4b | May 1 | May 14 | Oct 3 | 155 |
| Boscobel | 5a | May 3 | May 18 | Oct 7 | 157 |
| Marshfield | 4b | May 5 | May 20 | Oct 5 | 153 |
| Sheboygan | 5b | May 5 | May 21 | Oct 8 | 156 |
| Wausau Dwtn | 5a | May 6 | May 21 | Oct 4 | 151 |
| Eau Claire | 4b | May 8 | May 21 | Oct 4 | 149 |
| Wisconsin Rapids Alexander | 4b | May 8 | May 22 | Oct 1 | 146 |
| Grantsburg | 4a | May 11 | May 28 | Oct 1 | 143 |
| Ashland Kennedy | 5a | May 23 | Jun 6 | Sep 29 | 129 |
| Hayward | 4a | May 23 | Jun 6 | Sep 22 | 122 |
| Rhinelander Oneida | 4b | May 26 | Jun 8 | Sep 23 | 120 |
Dates are the 50% probability of a 32°F freeze (NOAA 1991–2020 normals); "90% safe after" is the date after which a later spring freeze happens in only 1 year in 10.
When to plant in Wisconsin
Using the statewide middle dates (last frost May 2, first frost Oct 7). Adjust for your town with the table above or the planting calendar.
| Plant | When to plant in Wisconsin |
|---|---|
| Tomatoes | May 9 – May 23 |
| Peas | Mar 21 – Apr 11; fall: Jul 15 – Aug 5 |
| Potatoes | Apr 4 – Apr 25 |
| Green beans | May 9 – May 23; fall: Jul 22 – Aug 5 |
| Garlic | Oct 7 – Nov 4 |
| Tulips | Sep 23 – Nov 4 |