Frost Dates: First and last frost dates for towner, nd
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 3.
- There is a 50% chance of being hit by a 32° frost starting around September 15
- You have a 80% chance of seeing 32° by September 26
- 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 4 | Oct 10 | Oct 15 | Oct 18 | Oct 22 | Oct 26 | Oct 29 | Nov 3 | Nov 9 |
First 20° | Sep 30 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 28 |
First 24° | Sep 18 | Sep 24 | Sep 28 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 14 | Oct 20 |
First 28° | Sep 6 | Sep 12 | Sep 16 | Sep 20 | Sep 24 | Sep 27 | Oct 1 | Oct 5 | Oct 11 |
First 32° | Aug 29 | Sep 3 | Sep 8 | Sep 11 | Sep 15 | Sep 18 | Sep 22 | Sep 26 | Oct 2 |
First 36° | Aug 17 | Aug 23 | Aug 27 | Aug 31 | Sep 3 | Sep 7 | Sep 10 | Sep 15 | Sep 21 |
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 23. 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 17, so we don't dare plant that early. We wait a few days and by June 1 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° | Apr 19 | Apr 16 | Apr 13 | Apr 10 | Apr 8 | Apr 6 | Apr 3 | Apr 1 | Mar 28 |
Last 20° | May 8 | May 2 | Apr 28 | Apr 24 | Apr 21 | Apr 17 | Apr 13 | Apr 9 | Apr 3 |
Last 24° | May 15 | May 9 | May 5 | May 1 | Apr 28 | Apr 24 | Apr 21 | Apr 16 | Apr 11 |
Last 28° | May 22 | May 17 | May 13 | May 10 | May 7 | May 4 | May 1 | Apr 28 | Apr 23 |
Last 32° | Jun 4 | May 29 | May 25 | May 22 | May 19 | May 16 | May 12 | May 8 | May 3 |
Last 36° | Jun 23 | Jun 15 | Jun 10 | Jun 5 | Jun 1 | May 27 | May 23 | May 17 | May 10 |
Data is provided by the NOAA National Centers for Environmental Information.