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