Frost Dates: First and last frost dates for Neihart, MT

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

ℹ️ How to read these charts for the fall

As summer ends in Neihart, MT, 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 25, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By September 5, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By September 17, 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 17 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 30 Oct 5 Oct 10 Oct 13 Oct 17 Oct 20 Oct 24 Oct 28 Nov 3
First 20° Sep 20 Sep 26 Sep 30 Oct 4 Oct 7 Oct 10 Oct 14 Oct 18 Oct 24
First 24° Sep 14 Sep 19 Sep 23 Sep 26 Sep 29 Oct 2 Oct 6 Oct 10 Oct 15
First 28° Sep 4 Sep 9 Sep 12 Sep 14 Sep 17 Sep 19 Sep 22 Sep 25 Sep 29
First 32° Aug 19 Aug 25 Aug 29 Sep 2 Sep 5 Sep 9 Sep 12 Sep 17 Sep 23
First 36° Aug 3 Aug 9 Aug 13 Aug 17 Aug 20 Aug 24 Aug 28 Sep 1 Sep 7

📍 Frost Dates for other nearby locations

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