Frost Dates: First and last frost dates for Laona, 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 July 1, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around June 12, 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 21 Apr 16 Apr 13 Apr 10 Apr 7 Apr 4 Apr 1 Mar 29 Mar 24
Last 20° May 2 Apr 27 Apr 24 Apr 20 Apr 18 Apr 15 Apr 11 Apr 8 Apr 3
Last 24° May 11 May 6 May 3 Apr 30 Apr 27 Apr 24 Apr 21 Apr 18 Apr 13
Last 28° May 31 May 26 May 21 May 18 May 15 May 11 May 8 May 3 Apr 28
Last 32° Jun 18 Jun 13 Jun 8 Jun 5 Jun 1 May 29 May 25 May 21 May 15
Last 36° Jul 1 Jun 25 Jun 20 Jun 16 Jun 12 Jun 9 Jun 5 May 31 May 25

ℹ️ How to read these charts for the fall

As summer ends in Laona, 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 8, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 17, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 27, 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 27 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 22 Oct 27 Oct 31 Nov 3 Nov 6 Nov 9 Nov 12 Nov 16 Nov 21
First 20° Oct 15 Oct 20 Oct 24 Oct 27 Oct 30 Nov 2 Nov 5 Nov 8 Nov 13
First 24° Sep 29 Oct 5 Oct 9 Oct 12 Oct 16 Oct 19 Oct 22 Oct 27 Nov 1
First 28° Sep 17 Sep 22 Sep 25 Sep 28 Oct 1 Oct 4 Oct 7 Oct 11 Oct 16
First 32° Sep 3 Sep 8 Sep 12 Sep 15 Sep 17 Sep 20 Sep 23 Sep 27 Oct 1
First 36° Aug 19 Aug 25 Aug 30 Sep 3 Sep 7 Sep 11 Sep 15 Sep 20 Sep 26

📍 Frost Dates for other nearby locations

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