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