Frost Dates: First and last frost dates for Arlington Univ Farm, 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 18, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around May 31, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before May 20, 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 14 Apr 10 Apr 7 Apr 4 Apr 2 Mar 30 Mar 28 Mar 25 Mar 20
Last 20° Apr 23 Apr 18 Apr 16 Apr 13 Apr 11 Apr 8 Apr 6 Apr 3 Mar 30
Last 24° May 4 Apr 29 Apr 26 Apr 23 Apr 20 Apr 17 Apr 14 Apr 11 Apr 6
Last 28° May 18 May 13 May 9 May 6 May 3 May 1 Apr 27 Apr 24 Apr 19
Last 32° Jun 8 May 31 May 26 May 22 May 18 May 14 May 9 May 4 Apr 27
Last 36° Jun 18 Jun 12 Jun 7 Jun 4 May 31 May 28 May 24 May 20 May 14

ℹ️ How to read these charts for the fall

As summer ends in Arlington Univ Farm, 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 15, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 25, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By October 6, 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 October 6 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 30 Nov 2 Nov 6 Nov 9 Nov 13 Nov 17 Nov 23
First 20° Oct 10 Oct 16 Oct 20 Oct 24 Oct 27 Oct 30 Nov 3 Nov 7 Nov 13
First 24° Sep 29 Oct 5 Oct 10 Oct 13 Oct 17 Oct 20 Oct 24 Oct 28 Nov 3
First 28° Sep 23 Sep 27 Sep 30 Oct 3 Oct 5 Oct 7 Oct 10 Oct 13 Oct 17
First 32° Sep 9 Sep 15 Sep 19 Sep 22 Sep 25 Sep 28 Oct 2 Oct 6 Oct 11
First 36° Aug 31 Sep 6 Sep 9 Sep 13 Sep 16 Sep 19 Sep 22 Sep 26 Oct 1

📍 Frost Dates for other nearby locations

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