Frost Dates: First and last frost dates for Martinsdale, 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 July 29. 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 July 4, so we don't dare plant that early. We wait a few days and by July 14 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° May 4 Apr 28 Apr 23 Apr 19 Apr 15 Apr 11 Apr 7 Apr 3 Mar 27
Last 20° May 15 May 10 May 6 May 3 Apr 30 Apr 27 Apr 24 Apr 21 Apr 16
Last 24° Jun 4 May 28 May 24 May 20 May 16 May 12 May 8 May 4 Apr 27
Last 28° Jun 21 Jun 15 Jun 10 Jun 6 Jun 3 May 30 May 26 May 21 May 15
Last 32° Jul 14 Jul 7 Jul 1 Jun 27 Jun 23 Jun 19 Jun 14 Jun 9 Jun 2
Last 36° Jul 29 Jul 24 Jul 20 Jul 17 Jul 14 Jul 11 Jul 8 Jul 4 Jun 29

How to read these charts for the fall
As your growing season comes to an end, the nightly temperatures for Martinsdale, 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 August 17, and by September 12 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 August 22.
  2. There is a 50% chance of being hit by a 32° frost starting around September 2
  3. You have a 80% chance of seeing 32° by September 12
  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 1 Oct 6 Oct 10 Oct 13 Oct 17 Oct 20 Oct 23 Oct 27 Nov 2
First 20° Sep 16 Sep 22 Sep 26 Sep 29 Oct 3 Oct 6 Oct 10 Oct 14 Oct 19
First 24° Sep 9 Sep 14 Sep 17 Sep 20 Sep 23 Sep 26 Sep 29 Oct 2 Oct 7
First 28° Sep 2 Sep 6 Sep 9 Sep 11 Sep 13 Sep 16 Sep 18 Sep 21 Sep 25
First 32° Aug 17 Aug 22 Aug 26 Aug 30 Sep 2 Sep 5 Sep 8 Sep 12 Sep 18
First 36° Aug 3 Aug 9 Aug 13 Aug 17 Aug 20 Aug 23 Aug 27 Aug 31 Sep 6

Frost Dates for other nearby locations
  • Martinsdale, MT
  • Wilsall, MT
  • Melville, MT
  • Neihart, MT
  • Harlowton, MT
  • Stanford, MT
  • Moccasin, MT
  • Livingston, MT
  • Raynesford, MT
  • Big Timber, MT

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