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