Frost Dates: First and last frost dates for Sandpoint, ID
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 1. 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 26, so we don't dare plant that early. We wait a few days and by June 9 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.
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
Last 16° | Mar 23 | Mar 14 | Mar 8 | Mar 3 | Feb 26 | Feb 21 | Feb 16 | Feb 10 | Feb 2 |
Last 20° | Apr 6 | Mar 28 | Mar 23 | Mar 18 | Mar 13 | Mar 8 | Mar 3 | Feb 25 | Feb 17 |
Last 24° | Apr 24 | Apr 18 | Apr 14 | Apr 10 | Apr 7 | Apr 3 | Mar 31 | Mar 27 | Mar 21 |
Last 28° | May 14 | May 9 | May 5 | May 2 | Apr 28 | Apr 25 | Apr 22 | Apr 18 | Apr 12 |
Last 32° | Jun 4 | May 29 | May 25 | May 22 | May 19 | May 16 | May 12 | May 8 | May 3 |
Last 36° | Jul 1 | Jun 24 | Jun 18 | Jun 13 | Jun 9 | Jun 5 | May 31 | May 26 | May 18 |
The charts on this page show the probabilities of receiving a certain temperature on a certain day. Some examples that might help:
- You have a small 20% chance of getting 32° by September 8.
- There is a 50% chance of being hit by a 32° frost starting around September 18
- You have a 80% chance of seeing 32° by September 28
- Said another way, you have a 1 in 5 chance at making it to that day without a 32° night.
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
First 16° | Oct 28 | Nov 8 | Nov 15 | Nov 22 | Nov 27 | Dec 3 | Dec 10 | Dec 17 | Dec 27 |
First 20° | Oct 16 | Oct 24 | Oct 30 | Nov 3 | Nov 8 | Nov 12 | Nov 17 | Nov 22 | Nov 30 |
First 24° | Sep 23 | Oct 2 | Oct 8 | Oct 13 | Oct 18 | Oct 23 | Oct 28 | Nov 3 | Nov 12 |
First 28° | Sep 20 | Sep 25 | Sep 29 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 20 |
First 32° | Sep 3 | Sep 8 | Sep 12 | Sep 15 | Sep 18 | Sep 21 | Sep 24 | Sep 28 | Oct 3 |
First 36° | Aug 19 | Aug 25 | Aug 30 | Sep 2 | Sep 6 | Sep 9 | Sep 13 | Sep 18 | Sep 24 |
Data is provided by the NOAA National Centers for Environmental Information.