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