Frost Dates: First and last frost dates for oakridge fish hatchery, 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 16. 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 12, so we don't dare plant that early. We wait a few days and by May 26 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° Feb 7 Jan 24 Jan 12 Dec 30 Dec 8 -- -- -- --
Last 20° Feb 15 Feb 4 Jan 27 Jan 19 Jan 12 Jan 4 Dec 26 Dec 8 --
Last 24° Mar 12 Feb 28 Feb 19 Feb 12 Feb 5 Jan 29 Jan 22 Jan 12 Dec 29
Last 28° Apr 21 Apr 11 Apr 4 Mar 29 Mar 24 Mar 19 Mar 13 Mar 6 Feb 24
Last 32° May 15 May 8 May 2 Apr 28 Apr 24 Apr 20 Apr 16 Apr 10 Apr 3
Last 36° Jun 16 Jun 9 Jun 4 May 30 May 26 May 22 May 17 May 12 May 5

How to read these charts for the fall
As your growing season comes to an end, the nightly temperatures for oakridge fish hatchery, 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 28, and by October 25 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 October 4.
  2. There is a 50% chance of being hit by a 32° frost starting around October 14
  3. You have a 80% chance of seeing 32° by October 25
  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° Dec 12 Dec 29 Jan 13 Jan 30 -- -- -- -- --
First 20° Nov 28 Dec 11 Dec 20 Dec 28 Jan 6 Jan 15 Jan 28 -- --
First 24° Nov 6 Nov 18 Nov 26 Dec 3 Dec 10 Dec 17 Dec 24 Jan 2 Jan 16
First 28° Oct 15 Oct 26 Nov 2 Nov 8 Nov 14 Nov 20 Nov 26 Dec 4 Dec 14
First 32° Sep 28 Oct 4 Oct 8 Oct 11 Oct 14 Oct 17 Oct 21 Oct 25 Oct 30
First 36° Sep 8 Sep 15 Sep 20 Sep 24 Sep 28 Oct 2 Oct 6 Oct 11 Oct 18

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