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