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