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