Frost Dates: First and last frost dates for Winter, WI

ℹ️ How to read these charts for the spring

As spring unfolds, the risk of frost gradually decreases each day until your tender plants are finally safe. The probabilities shown in the chart help you make smart decisions about when to plant.

While frost typically forms at 32°F, tender plants can be damaged even when temperatures are slightly higher. Air temperatures are often measured several feet above the ground, but temperatures at plant level can be several degrees colder. Protected areas like porches help by blocking radiational cooling. Given these variables, we consider 36°F the "caution zone" for frost-sensitive plants.

Key dates for your spring planting:

  • By June 27, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around June 11, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before June 1, there's still an 80% risk of frost — too early for tomatoes and other tender plants unless you're prepared to protect them

If the 10-day forecast shows no temperatures below 40°F, you might safely plant earlier than the above dates suggest. Many gardeners watch for this weather window to get a head start on the growing season.

In the Spring
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
Last 16° Apr 19 Apr 15 Apr 12 Apr 10 Apr 8 Apr 6 Apr 3 Apr 1 Mar 28
Last 20° May 1 Apr 26 Apr 22 Apr 19 Apr 16 Apr 13 Apr 10 Apr 7 Apr 2
Last 24° May 17 May 12 May 8 May 4 May 1 Apr 28 Apr 24 Apr 20 Apr 14
Last 28° Jun 2 May 27 May 23 May 20 May 17 May 13 May 10 May 6 Apr 30
Last 32° Jun 14 Jun 9 Jun 5 Jun 2 May 30 May 27 May 24 May 21 May 16
Last 36° Jun 27 Jun 21 Jun 18 Jun 14 Jun 11 Jun 8 Jun 5 Jun 1 May 27

ℹ️ How to read these charts for the fall

As summer ends in Winter, WI, nighttime temperatures begin to drop, and your risk of frost increases with each passing day. Knowing when to expect frost helps you harvest sensitive crops and extend your growing season with protection methods.

The chart below shows the probability of experiencing specific temperatures on various dates. Here's what this means for your garden:

1
Early warning: Around September 7, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 16, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 25, there's an 80% chance of seeing 32°F — most tender plants will be damaged without protection
4
Another perspective: You have only a 1 in 5 chance of making it past September 25 without a freezing night

These probabilities help you time your end-of-season harvests and know when to apply protective measures like row covers, cloches, or cold frames to extend your harvest.

In the Fall
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
First 16° Oct 20 Oct 25 Oct 28 Oct 31 Nov 3 Nov 6 Nov 8 Nov 12 Nov 16
First 20° Oct 11 Oct 15 Oct 19 Oct 22 Oct 25 Oct 28 Oct 31 Nov 3 Nov 8
First 24° Sep 26 Oct 1 Oct 5 Oct 7 Oct 10 Oct 13 Oct 16 Oct 19 Oct 24
First 28° Sep 20 Sep 24 Sep 27 Sep 29 Oct 1 Oct 3 Oct 6 Oct 8 Oct 12
First 32° Sep 2 Sep 7 Sep 10 Sep 13 Sep 16 Sep 19 Sep 22 Sep 25 Sep 30
First 36° Aug 20 Aug 25 Aug 29 Sep 1 Sep 4 Sep 7 Sep 11 Sep 14 Sep 20

📍 Frost Dates for other nearby locations

Or enter a new zipcode:

Data is provided by the NOAA National Centers for Environmental Information.