Frost Dates: First and last frost dates for Mt Carroll, IL
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 17.
- There is a 50% chance of being hit by a 32° frost starting around September 26
- 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 27 | Nov 1 | Nov 5 | Nov 9 | Nov 13 | Nov 17 | Nov 21 | Nov 28 |
First 20° | Oct 11 | Oct 17 | Oct 22 | Oct 26 | Oct 30 | Nov 2 | Nov 6 | Nov 11 | Nov 17 |
First 24° | Sep 29 | Oct 4 | Oct 8 | Oct 12 | Oct 15 | Oct 18 | Oct 22 | Oct 26 | Nov 1 |
First 28° | Sep 20 | Sep 26 | Sep 30 | Oct 3 | Oct 7 | Oct 10 | Oct 13 | Oct 17 | Oct 23 |
First 32° | Sep 12 | Sep 17 | Sep 20 | Sep 23 | Sep 26 | Sep 29 | Oct 2 | Oct 6 | Oct 10 |
First 36° | Sep 4 | Sep 9 | Sep 12 | Sep 15 | Sep 17 | Sep 20 | Sep 22 | Sep 25 | Sep 30 |
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 8. 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 19 | Apr 12 | Apr 7 | Apr 3 | Mar 30 | Mar 26 | Mar 22 | Mar 18 | Mar 11 |
Last 20° | Apr 19 | Apr 15 | Apr 11 | Apr 8 | Apr 6 | Apr 3 | Mar 31 | Mar 28 | Mar 23 |
Last 24° | Apr 29 | Apr 24 | Apr 20 | Apr 17 | Apr 14 | Apr 11 | Apr 8 | Apr 4 | Mar 30 |
Last 28° | May 16 | May 10 | May 6 | May 2 | Apr 29 | Apr 25 | Apr 22 | Apr 18 | Apr 12 |
Last 32° | May 28 | May 22 | May 18 | May 15 | May 12 | May 8 | May 5 | May 1 | Apr 25 |
Last 36° | Jun 8 | Jun 2 | May 29 | May 26 | May 23 | May 19 | May 16 | May 12 | May 6 |
Data is provided by the NOAA National Centers for Environmental Information.