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