Frost Dates: First and last frost dates for Hillsboro, 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 24.
- 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 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° | Oct 27 | Nov 2 | Nov 6 | Nov 10 | Nov 13 | Nov 17 | Nov 21 | Nov 25 | Dec 1 |
First 20° | Oct 15 | Oct 21 | Oct 25 | Oct 28 | Nov 1 | Nov 4 | Nov 8 | Nov 12 | Nov 18 |
First 24° | Oct 4 | Oct 10 | Oct 14 | Oct 18 | Oct 22 | Oct 25 | Oct 29 | Nov 2 | Nov 8 |
First 28° | Sep 23 | Sep 28 | Oct 2 | Oct 5 | Oct 7 | Oct 10 | Oct 13 | Oct 17 | Oct 21 |
First 32° | Sep 20 | Sep 24 | Sep 26 | Sep 28 | Sep 30 | Oct 2 | Oct 4 | Oct 6 | Oct 9 |
First 36° | Sep 9 | Sep 12 | Sep 15 | Sep 17 | Sep 19 | Sep 21 | Sep 23 | Sep 25 | Sep 29 |
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 11. 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 24 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 4 | Mar 31 | Mar 28 | Mar 24 | Mar 21 | Mar 18 | Mar 14 | Mar 9 |
Last 20° | Apr 18 | Apr 14 | Apr 11 | Apr 8 | Apr 6 | Apr 4 | Apr 1 | Mar 29 | Mar 25 |
Last 24° | Apr 24 | Apr 20 | Apr 17 | Apr 14 | Apr 12 | Apr 10 | Apr 7 | Apr 4 | Mar 31 |
Last 28° | May 13 | May 8 | May 4 | May 1 | Apr 28 | Apr 25 | Apr 22 | Apr 18 | Apr 13 |
Last 32° | May 30 | May 24 | May 20 | May 16 | May 13 | May 10 | May 6 | May 2 | Apr 26 |
Last 36° | Jun 11 | Jun 5 | May 31 | May 27 | May 24 | May 20 | May 16 | May 12 | May 5 |
Data is provided by the NOAA National Centers for Environmental Information.