Frost Dates: First and last frost dates for La Grande, OR

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 30. 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 23, so we don't dare plant that early. We wait a few days and by June 7 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° Mar 10 Mar 2 Feb 24 Feb 19 Feb 14 Feb 9 Feb 4 Jan 29 Jan 21
Last 20° Mar 31 Mar 22 Mar 16 Mar 11 Mar 6 Mar 1 Feb 24 Feb 18 Feb 9
Last 24° Apr 24 Apr 18 Apr 13 Apr 9 Apr 6 Apr 2 Mar 29 Mar 25 Mar 19
Last 28° May 18 May 11 May 6 May 1 Apr 27 Apr 23 Apr 19 Apr 14 Apr 7
Last 32° Jun 18 Jun 9 Jun 2 May 27 May 21 May 16 May 10 May 2 Apr 23
Last 36° Jun 30 Jun 22 Jun 16 Jun 11 Jun 7 Jun 2 May 29 May 23 May 15

How to read these charts for the fall
As your growing season comes to an end, the nightly temperatures for La Grande, OR 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 11, and by October 3 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 15.
  2. There is a 50% chance of being hit by a 32° frost starting around September 24
  3. You have a 80% chance of seeing 32° by October 3
  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° Nov 2 Nov 12 Nov 19 Nov 25 Dec 1 Dec 7 Dec 13 Dec 20 Dec 30
First 20° Oct 18 Oct 26 Nov 1 Nov 6 Nov 11 Nov 16 Nov 21 Nov 27 Dec 5
First 24° Oct 6 Oct 12 Oct 17 Oct 20 Oct 24 Oct 27 Oct 31 Nov 5 Nov 11
First 28° Sep 24 Sep 29 Oct 3 Oct 6 Oct 8 Oct 11 Oct 14 Oct 18 Oct 23
First 32° Sep 11 Sep 15 Sep 19 Sep 22 Sep 24 Sep 27 Sep 30 Oct 3 Oct 8
First 36° Aug 27 Sep 2 Sep 6 Sep 10 Sep 14 Sep 17 Sep 21 Sep 25 Oct 1

Frost Dates for other nearby locations
  • Union, OR
  • Elgin, OR
  • Cove, OR
  • Baker City, OR
  • Wallowa, OR
  • Mason Dam, OR
  • Pendleton Br, OR
  • Milton Freewater, OR
  • Pilot Rock, OR
  • Pendleton Dwtn, OR

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