Frost dates and when to plant in Wisconsin

United States

In Wisconsin the last spring frost comes between 27 April (Milwaukee) and 29 April (Green Bay) — the median of 2016–2025 in 4 cities. The first autumn frost comes between 24 October (Eau Claire) and 1 November (Milwaukee). The frost-free season lasts 179–188 days. Tomato: plant out into open ground 16 May – 12 July, earliest in Madison, latest in Milwaukee.

Frost dates by city in Wisconsin

City	Last spring frost	First autumn frost	Frost-free days	Climate zone	Tomato: window
Madison	27 April	27 October	183	150–209 frost-free days	16 May – 7 July
Milwaukee	27 April	1 November	188	150–209 frost-free days	19 May – 12 July
Eau Claire	28 April	24 October	179	150–209 frost-free days	16 May – 4 July
Green Bay	29 April	30 October	184	150–209 frost-free days	19 May – 10 July

Median of 2016–2025 for the 25 km grid cell of the city: the last day at or below 0 °C in spring and the first in autumn (ERA5 reanalysis via Open-Meteo). In a cold year a frost can come a week or two later — Greenly warns 48 hours ahead.

When to plant in Wisconsin: windows by crop

The earliest start and the latest end among the cities here, each with its city; every city’s own window is on its page. Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

Crop	Planting out or sowing
Tomato	16 May (Madison) – 12 July (Milwaukee)
Cucumber	27 May (Green Bay) – 17 August (Milwaukee)
Bell Pepper, Eggplant	27 May (Green Bay) – 12 July (Milwaukee)
Zucchini	27 May (Green Bay) – 15 August (Milwaukee)
Pumpkin	27 May (Green Bay) – 7 July (Milwaukee)
Watermelon	27 May (Green Bay) – 23 July (Milwaukee)
Peas	6 April (Milwaukee) – 19 August (Milwaukee)
Garlic, Tulip, Daffodil, Crocus, Hyacinth	Autumn planting: 24 September (Eau Claire) – 25 November (Milwaukee)

Weather by month in Wisconsin

Across the 4 cities the warmest month is July (average days 27.6 … 28 °C) and the coldest January (average nights -12.2 … -8.2 °C). Every city averages below 0 °C at night in December–March.

Month	Day, °C	Night, °C	Rain, mm
January	-3.5 … -0.9 °C	-12.2 … -8.2 °C	42
February	-1.1 … 1.7 °C	-11.7 … -7.1 °C	40
March	6 … 8.2 °C	-3.7 … -1.7 °C	77
April	11.9 … 13.7 °C	1.6 … 3 °C	94
May	18.7 … 20.6 °C	8.8 … 9.9 °C	109
June	25.4 … 26.5 °C	15.2 … 16.2 °C	111
July	27.6 … 28 °C	17.5 … 18.4 °C	101
August	26 … 26.7 °C	16.6 … 17.8 °C	86
September	23 … 23.6 °C	13.7 … 14.9 °C	91
October	14.8 … 16.2 °C	6.2 … 8.3 °C	84
November	6.2 … 8.2 °C	-1.5 … 0.9 °C	49
December	-0.9 … 2.2 °C	-8.9 … -4.8 °C	48

Day and night: the lowest … highest monthly average among the cities; rain: the middle city (ERA5 via Open-Meteo).

Frost dates and when to plant in Wisconsin

Frost dates by city in Wisconsin

When to plant in Wisconsin: windows by crop

Weather by month in Wisconsin

What to plant month by month: the Northeast and Midwest

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