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