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