Frost Dates: First and last frost dates for Raymond Border Stn, 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 8. 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 June 3, so we don't dare plant that early. We wait a few days and by June 17 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 22 Apr 16 Apr 12 Apr 9 Apr 5 Apr 2 Mar 30 Mar 26 Mar 20
Last 20° Apr 29 Apr 24 Apr 20 Apr 17 Apr 14 Apr 11 Apr 8 Apr 5 Mar 31
Last 24° May 12 May 7 May 3 Apr 30 Apr 27 Apr 24 Apr 20 Apr 17 Apr 11
Last 28° May 27 May 22 May 18 May 16 May 13 May 10 May 7 May 4 Apr 29
Last 32° Jun 20 Jun 13 Jun 8 Jun 4 May 31 May 27 May 22 May 17 May 10
Last 36° Jul 8 Jun 30 Jun 25 Jun 21 Jun 17 Jun 12 Jun 8 Jun 3 May 27

How to read these charts for the fall
As your growing season comes to an end, the nightly temperatures for Raymond Border Stn, 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 23 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 16
  3. You have a 80% chance of seeing 32° by September 23
  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 8 Oct 13 Oct 17 Oct 21 Oct 24 Oct 27 Oct 31 Nov 4 Nov 10
First 20° Sep 25 Oct 1 Oct 5 Oct 9 Oct 13 Oct 16 Oct 20 Oct 25 Oct 31
First 24° Sep 18 Sep 23 Sep 27 Sep 30 Oct 4 Oct 7 Oct 10 Oct 14 Oct 19
First 28° Sep 12 Sep 16 Sep 19 Sep 22 Sep 24 Sep 27 Sep 29 Oct 2 Oct 6
First 32° Sep 4 Sep 8 Sep 11 Sep 13 Sep 16 Sep 18 Sep 20 Sep 23 Sep 27
First 36° Aug 16 Aug 22 Aug 27 Aug 30 Sep 3 Sep 6 Sep 10 Sep 14 Sep 20

Frost Dates for other nearby locations
  • Martinsdale, MT
  • Neihart, MT
  • Moccasin, MT
  • Raynesford, MT
  • Lennep, MT
  • Denton, MT
  • Shonkin, MT
  • Harlowton, MT
  • Geraldine, MT
  • Melville, MT

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