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

How to read these charts for the spring
As the growing season approaches, the days get longer, the weather begins to warm up, and the nights start being less cold. You're still getting frost, but the chance of nightly frosts gets less and less with each passing day. Eventually, the frost stops, and this is when your tender plants are fully safe. So, how do you plan for this? The probabilities on this page help you assess your risk of frost on any given day.

What's a safe temperature for tender plants? When the nightly temperature falls, frost can form, even above 32°, because the air is colder high above the ground and the frost can form up there and then fall down onto your garden and do some damage, even if it's 36° on the ground. So many factors come into play, including wind, concrete, houses, trees and other structures, etc etc etc. Because of all this, you might want to consider 36° as "the danger zone".

In your average springtime, you have a 90% chance that there will be no 36° nights by June 25. In other words, you can pretty much count on being safe from frost by that day. But we want to get those tomatoes in the ground as soon as possible, right? We see that there's still an 80% chance of 36° on May 22, so we don't dare plant that early. We wait a few days and by June 5 we are at the 50/50 point. At this point, we are close and we can start watching the weather forecast. If the upcoming week's forecast doesn't show below 40°, then it's probably okay to risk planting out your plants.

In the Spring
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
Last 16° Apr 20 Apr 15 Apr 11 Apr 8 Apr 5 Apr 2 Mar 30 Mar 26 Mar 21
Last 20° May 4 Apr 29 Apr 25 Apr 21 Apr 18 Apr 15 Apr 11 Apr 7 Apr 2
Last 24° May 10 May 6 May 4 May 1 Apr 29 Apr 27 Apr 24 Apr 21 Apr 17
Last 28° May 24 May 19 May 15 May 12 May 8 May 5 May 2 Apr 28 Apr 22
Last 32° Jun 11 Jun 4 May 30 May 26 May 22 May 18 May 14 May 9 May 2
Last 36° Jun 25 Jun 18 Jun 13 Jun 9 Jun 5 Jun 1 May 27 May 22 May 16

How to read these charts for the fall
As your growing season comes to an end, the nightly temperatures for Terry, MT start to go down, and therefore every day that goes by increases the chance that you'll get frost. Your risk of frost really begins around September 4, and by September 22 you're almost certain to have received at least one frost event.

The charts on this page show the probabilities of receiving a certain temperature on a certain day. Some examples that might help:

  1. You have a small 20% chance of getting 32° by September 8.
  2. There is a 50% chance of being hit by a 32° frost starting around September 15
  3. You have a 80% chance of seeing 32° by September 22
  4. Said another way, you have a 1 in 5 chance at making it to that day without a 32° night.
In the Fall
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
First 16° Oct 5 Oct 11 Oct 15 Oct 19 Oct 22 Oct 25 Oct 29 Nov 2 Nov 8
First 20° Sep 26 Oct 2 Oct 6 Oct 9 Oct 13 Oct 16 Oct 20 Oct 24 Oct 30
First 24° Sep 16 Sep 22 Sep 26 Sep 30 Oct 4 Oct 7 Oct 11 Oct 15 Oct 21
First 28° Sep 7 Sep 12 Sep 15 Sep 18 Sep 21 Sep 24 Sep 27 Oct 1 Oct 6
First 32° Sep 4 Sep 8 Sep 11 Sep 13 Sep 15 Sep 17 Sep 20 Sep 22 Sep 26
First 36° Aug 22 Aug 27 Aug 31 Sep 3 Sep 6 Sep 9 Sep 12 Sep 16 Sep 21

Frost Dates for other nearby locations
  • Terry, MT
  • Circle, MT
  • Brockway, MT
  • Miles City, MT
  • Mizpah, MT
  • Glendive, MT
  • Rock Springs, MT
  • Bloomfield, MT
  • Vida, MT
  • Plevna, MT

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