When Is the Last Frost in Wisconsin?
The average last spring frost in Wisconsin falls between April 26 and May 19 for most ZIP codes, with a statewide median of May 4. At the average date a later frost is still a coin flip, so tender plants wait for the safer 90% date.
| City | Last frost | 90% safe after | First frost | Growing season |
|---|---|---|---|---|
| Milwaukee | Apr 26 | May 12 | Oct 18 | 173 days |
| Madison | May 1 | May 17 | Oct 9 | 161 days |
| Green Bay | May 7 | May 22 | Oct 9 | 154 days |
| Kenosha | Apr 28 | May 13 | Oct 19 | 174 days |
| Racine | Apr 24 | May 10 | Oct 24 | 180 days |
| Appleton | May 4 | May 20 | Oct 6 | 154 days |
| Eau Claire | May 8 | May 21 | Oct 4 | 149 days |
| Waukesha | Apr 30 | May 15 | Oct 14 | 164 days |
| Oshkosh | Apr 24 | May 8 | Oct 20 | 178 days |
| Janesville | Apr 26 | May 11 | Oct 15 | 170 days |
| La Crosse | Apr 23 | May 6 | Oct 17 | 177 days |
| Sheboygan | May 2 | May 19 | Oct 21 | 169 days |
| Fond du Lac | May 1 | May 17 | Oct 12 | 162 days |
| Wausau | May 6 | May 21 | Oct 4 | 150 days |
| Manitowoc | Apr 30 | May 15 | Oct 20 | 171 days |
| West Bend | May 1 | May 18 | Oct 12 | 161 days |
| Superior | May 18 | Jun 3 | Oct 3 | 135 days |
| Stevens Point | May 4 | May 20 | Oct 7 | 155 days |
| Medford | May 11 | May 26 | Oct 1 | 141 days |
Last and first frost: 50% (median) dates of the last spring and first fall 32 °F night. 90% safe after: only a 10% chance of a later spring frost. First frost dates in January fall in the following winter. Each city uses the NOAA station nearest the ZIP code closest to its center.
Across all 204 Wisconsin weather stations with frost records, median last frost dates run from April 19 at Kenosha, WI to June 3 at North Pelican, WI. Elevation, valleys that collect cold air and distance from large water bodies explain most of the spread, so a garden a few miles from a listed city can differ by a week or more. The ZIP code lookup above uses the same NOAA data as the frost date calculator for every US ZIP code.
When Is the First Frost in Wisconsin?
The average first fall frost in Wisconsin arrives between September 28 and October 18 for most ZIP codes, with a median of October 7. Tomatoes, peppers, basil and squash are damaged at 32 °F, so harvest or cover them before then.
Fall frost can come early: Milwaukee has a 10% chance of frost before October 2, Madison has a 10% chance of frost before September 26 and Green Bay has a 10% chance of frost before September 23. Hardy crops such as kale, spinach and cabbage tolerate light frosts and keep producing after the first frost date.
When to Plant Tomatoes in Wisconsin?
Transplant tomatoes in Wisconsin 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: May 3 – May 10 in Milwaukee, May 8 – May 15 in Madison and May 14 – May 21 in Green Bay. Start seeds indoors 6 to 8 weeks before the last frost.
| City | Start seeds indoors | Transplant outdoors | Lowest-risk transplant |
|---|---|---|---|
| Milwaukee | Mar 1 – Mar 15 | May 3 – May 10 | after May 12 |
| Madison | Mar 6 – Mar 20 | May 8 – May 15 | after May 17 |
| Green Bay | Mar 12 – Mar 26 | May 14 – May 21 | after May 22 |
| Kenosha | Mar 3 – Mar 17 | May 5 – May 12 | after May 13 |
| Racine | Feb 27 – Mar 13 | May 1 – May 8 | after May 10 |
| Appleton | Mar 9 – Mar 23 | May 11 – May 18 | after May 20 |
| Eau Claire | Mar 13 – Mar 27 | May 15 – May 22 | after May 21 |
| Waukesha | Mar 5 – Mar 19 | May 7 – May 14 | after May 15 |
| Oshkosh | Feb 27 – Mar 13 | May 1 – May 8 | after May 8 |
| Janesville | Mar 1 – Mar 15 | May 3 – May 10 | after May 11 |
| La Crosse | Feb 26 – Mar 12 | Apr 30 – May 7 | after May 6 |
| Sheboygan | Mar 7 – Mar 21 | May 9 – May 16 | after May 19 |
| Fond du Lac | Mar 6 – Mar 20 | May 8 – May 15 | after May 17 |
| Wausau | Mar 11 – Mar 25 | May 13 – May 20 | after May 21 |
| Manitowoc | Mar 5 – Mar 19 | May 7 – May 14 | after May 15 |
| West Bend | Mar 6 – Mar 20 | May 8 – May 15 | after May 18 |
| Superior | Mar 23 – Apr 6 | May 25 – Jun 1 | after Jun 3 |
| Stevens Point | Mar 9 – Mar 23 | May 11 – May 18 | after May 20 |
| Medford | Mar 16 – Mar 30 | May 18 – May 25 | after May 26 |
Indoors: 6–8 weeks before the average last frost. Outdoors: 1–2 weeks after it. Lowest-risk: after the date with only a 10% chance of a later frost. Rules of thumb; check the 10-day forecast and wait for soil near 60 °F.
Tomatoes stall below about 50 °F at night and are killed by frost, so a week or two of waiting after the average date costs little. The tomato plant care guide covers light, watering and feeding once plants are in the ground.
What Can You Plant in Milwaukee and When?
Milwaukee's average last frost of April 26 anchors its spring planting calendar: peas and spinach go in from March 15, broccoli and lettuce transplants from March 29, and tomatoes, peppers and squash after May 3.
| Crop | Start seeds indoors | Plant outdoors | Frost tolerance |
|---|---|---|---|
| Peas | — | Mar 15 – Mar 29direct sow, 4–6 weeks before last frost | hardy |
| Spinach | — | Mar 15 – Apr 5direct sow, 3–6 weeks before last frost | hardy |
| Radishes | — | Mar 22 – Apr 5direct sow, 3–5 weeks before last frost | hardy |
| Onions (sets) | — | Mar 29 – Apr 12plant, 2–4 weeks before last frost | hardy |
| Potatoes | — | Mar 29 – Apr 12plant, 2–4 weeks before last frost | half-hardy |
| Broccoli & cabbage | Mar 1 – Mar 15 | Mar 29 – Apr 12transplant, 2–4 weeks before last frost | hardy |
| Lettuce | Mar 15 – Mar 29 | Mar 29 – Apr 12transplant, 2–4 weeks before last frost | hardy |
| Beets | — | Mar 29 – Apr 12direct sow, 2–4 weeks before last frost | half-hardy |
| Carrots | — | Apr 5 – Apr 12direct sow, 2–3 weeks before last frost | half-hardy |
| Tomatoes | Mar 1 – Mar 15 | May 3 – May 10transplant, 1–2 weeks after last frost | tender |
| Basil | Mar 1 – Mar 15 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Peppers | Feb 15 – Mar 1 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
| Eggplant | Feb 15 – Mar 1 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
| Green beans | — | May 3 – May 17direct sow, 1–3 weeks after last frost | tender |
| Sweet corn | — | May 3 – May 17direct sow, 1–3 weeks after last frost | tender |
| Cucumbers | Mar 29 – Apr 5 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Squash & zucchini | Mar 29 – Apr 5 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Watermelon | Mar 29 – Apr 5 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
Dates for Milwaukee (last frost Apr 26, NOAA station Mt Mary College, WI, 3 miles from ZIP 53210). General rules of thumb; wait for soil near 50 °F for most seeds and 60 °F for beans, corn and squash.
How Long Is the Growing Season in Wisconsin?
The frost-free growing season in Wisconsin lasts about 132 to 173 days for most ZIP codes, with a median of 154 days. Among the listed cities, Superior has the shortest season at 135 days and Racine the longest at 180.
Season length decides which varieties ripen: compare it with the “days to maturity” on seed packets, counted from transplanting for tomatoes and peppers. NOAA stations in Wisconsin range from 106 days at North Pelican, WI to 192 days at Milwaukee Mitchell AP, WI. Planning beds before the season starts helps in short seasons — a plant spacing calculator for vegetable beds shows how many transplants fit.
What Hardiness Zones Are in Wisconsin?
Wisconsin spans USDA hardiness zones 3b to 6a, with zone 5b the most common. Zones describe winter cold and decide which perennials survive, while frost dates set when to plant annual vegetables and flowers.
The Wisconsin planting zone map with the zone of each city shows how the zones are spread across the state and which plants are hardy in all of them.
Frequently Asked Questions
- When is the last frost in Wisconsin?
- The average last spring frost in Wisconsin falls between April 26 and May 19 for most ZIP codes, with a statewide median of May 4. Among major cities it ranges from April 23 in La Crosse to May 18 in Superior.
- When is the last frost in Milwaukee, Wisconsin?
- Milwaukee's average last spring frost is April 26, and by May 12 the chance of a later frost drops to 10%. Its first fall frost averages October 18, giving a 173-day growing season (NOAA station Mt Mary College, WI).
- When should you plant tomatoes in Wisconsin?
- Transplant tomatoes in Wisconsin 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: May 3 – May 10 in Milwaukee, May 8 – May 15 in Madison and May 14 – May 21 in Green Bay. Start seeds indoors 6 to 8 weeks before the last frost.
- When is the first frost in Wisconsin?
- The average first fall frost in Wisconsin arrives between September 28 and October 18 for most ZIP codes, with a median of October 7. Harvest tender crops such as tomatoes, peppers and basil before then or cover them on cold nights.
- How long is the growing season in Wisconsin?
- The frost-free growing season in Wisconsin lasts about 132 to 173 days for most ZIP codes, with a median of 154 days, from 135 days in Superior to 180 days in Racine.
Frost data: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals (32 °F freeze dates by probability). ZIP code and city locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. Planting windows are general rules of thumb. PlantoScan is not affiliated with or endorsed by these agencies.