Frost Dates: First and last frost dates for Ashland Exp 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 23, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around June 9, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before May 31, 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 14 Apr 11 Apr 8 Apr 5 Apr 2 Mar 30 Mar 27 Mar 22
Last 20° May 3 Apr 28 Apr 24 Apr 21 Apr 18 Apr 15 Apr 11 Apr 8 Apr 2
Last 24° May 15 May 9 May 5 May 2 Apr 29 Apr 26 Apr 23 Apr 19 Apr 13
Last 28° Jun 1 May 26 May 22 May 19 May 16 May 13 May 9 May 5 Apr 30
Last 32° Jun 17 Jun 12 Jun 7 Jun 4 Jun 1 May 28 May 25 May 21 May 15
Last 36° Jun 23 Jun 18 Jun 14 Jun 12 Jun 9 Jun 6 Jun 3 May 31 May 26

ℹ️ How to read these charts for the fall

As summer ends in Ashland Exp 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 16, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 23, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 30, 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 30 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 26 Oct 30 Nov 2 Nov 5 Nov 7 Nov 10 Nov 12 Nov 16 Nov 20
First 20° Oct 14 Oct 18 Oct 22 Oct 25 Oct 27 Oct 30 Nov 2 Nov 6 Nov 10
First 24° Oct 2 Oct 7 Oct 11 Oct 15 Oct 18 Oct 21 Oct 25 Oct 29 Nov 3
First 28° Sep 19 Sep 23 Sep 26 Sep 29 Oct 2 Oct 4 Oct 7 Oct 10 Oct 15
First 32° Sep 12 Sep 16 Sep 18 Sep 21 Sep 23 Sep 25 Sep 28 Sep 30 Oct 4
First 36° Aug 28 Sep 2 Sep 6 Sep 9 Sep 12 Sep 15 Sep 18 Sep 22 Sep 27

📍 Frost Dates for other nearby locations

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