Frost Dates: First and last frost dates for Grouse, ID

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 29, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around July 18, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before July 11, 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° May 9 May 3 Apr 29 Apr 25 Apr 22 Apr 19 Apr 15 Apr 11 Apr 5
Last 20° May 22 May 17 May 13 May 10 May 7 May 4 May 1 Apr 27 Apr 22
Last 24° Jun 18 Jun 10 Jun 4 May 30 May 26 May 21 May 16 May 10 May 2
Last 28° Jul 13 Jul 5 Jun 29 Jun 24 Jun 19 Jun 14 Jun 9 Jun 3 May 26
Last 32° Jul 20 Jul 15 Jul 12 Jul 9 Jul 6 Jul 3 Jun 30 Jun 26 Jun 22
Last 36° Jul 29 Jul 26 Jul 23 Jul 21 Jul 18 Jul 16 Jul 14 Jul 11 Jul 7

ℹ️ How to read these charts for the fall

As summer ends in Grouse, ID, 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 August 13, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By August 24, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 4, 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 4 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° Sep 24 Sep 30 Oct 3 Oct 6 Oct 10 Oct 13 Oct 16 Oct 19 Oct 25
First 20° Sep 9 Sep 15 Sep 19 Sep 22 Sep 25 Sep 28 Oct 1 Oct 5 Oct 11
First 24° Aug 30 Sep 5 Sep 9 Sep 13 Sep 16 Sep 20 Sep 23 Sep 27 Oct 3
First 28° Aug 18 Aug 24 Aug 28 Sep 1 Sep 4 Sep 7 Sep 11 Sep 15 Sep 21
First 32° Aug 7 Aug 13 Aug 17 Aug 21 Aug 24 Aug 27 Aug 31 Sep 4 Sep 10
First 36° Jul 31 Aug 3 Aug 6 Aug 9 Aug 11 Aug 13 Aug 16 Aug 18 Aug 22

📍 Frost Dates for other nearby locations

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