First and last freeze/frost dates for Chicago, IL ,United States

First and last freeze/frost dates for:
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Each winter, on average, your risk of frost is from
October 13 through April 25.

Almost certainly, however, you will receive frost from October 28 through April 10.

You are almost guaranteed that you will not get frost from May 10 through September 28.

Your frost-free growing season is around 171 days.

Detailed station data* follows:

Chicago Ohare Wso Ap, IL (Cook county):

Temperature10%20%30%40%50%60%70%80%90%
Spring 32° May 10 May 5 May 1 Apr 28 Apr 25 Apr 22 Apr 19 Apr 15 Apr 10
Spring 28° Apr 24 Apr 20 Apr 17 Apr 14 Apr 12 Apr 10 Apr 7 Apr 4 Mar 31
Spring 24° Apr 15 Apr 11 Apr 8 Apr 6 Apr 3 Apr 1 Mar 29 Mar 26 Mar 22
Fall 32° Sep 28 Oct 3 Oct 7 Oct 10 Oct 13 Oct 16 Oct 19 Oct 23 Oct 28
Fall 28° Oct 8 Oct 14 Oct 19 Oct 23 Oct 26 Oct 30 Nov 2 Nov 6 Nov 13
Fall 24° Oct 24 Oct 29 Nov 1 Nov 5 Nov 8 Nov 11 Nov 15 Nov 19 Nov 24

Waukegan, IL (Lake county):

Temperature10%20%30%40%50%60%70%80%90%
Spring 32° May 12 May 7 May 3 Apr 30 Apr 27 Apr 24 Apr 21 Apr 17 Apr 12
Spring 28° Apr 27 Apr 23 Apr 20 Apr 17 Apr 15 Apr 13 Apr 10 Apr 7 Apr 3
Spring 24° Apr 16 Apr 13 Apr 10 Apr 8 Apr 6 Apr 4 Apr 2 Mar 31 Mar 27
Fall 32° Sep 28 Oct 4 Oct 8 Oct 12 Oct 15 Oct 18 Oct 22 Oct 26 Oct 31
Fall 28° Oct 11 Oct 17 Oct 21 Oct 24 Oct 27 Oct 30 Nov 2 Nov 6 Nov 11
Fall 24° Oct 24 Oct 29 Nov 1 Nov 4 Nov 7 Nov 10 Nov 13 Nov 17 Nov 22

Barrington 1 Nw, IL (Lake county):

Temperature10%20%30%40%50%60%70%80%90%
Spring 32° May 21 May 14 May 9 May 5 May 1 Apr 28 Apr 24 Apr 19 Apr 12
Spring 28° May 6 May 1 Apr 27 Apr 23 Apr 20 Apr 17 Apr 13 Apr 9 Apr 4
Spring 24° Apr 18 Apr 14 Apr 12 Apr 9 Apr 7 Apr 5 Apr 3 Mar 31 Mar 28
Fall 32° Sep 25 Sep 30 Oct 3 Oct 6 Oct 9 Oct 11 Oct 14 Oct 18 Oct 22
Fall 28° Oct 2 Oct 8 Oct 13 Oct 17 Oct 21 Oct 25 Oct 29 Nov 2 Nov 9
Fall 24° Oct 16 Oct 22 Oct 26 Oct 30 Nov 1 Nov 4 Nov 8 Nov 12 Nov 17

* This station data is available courtesy the National Climatic Data Center.

For each weather station, you will see a temperature along with tables of data organized into percentage columns. The percentage column tells you the probability that you will experience that row's temperature on or near that date. Here are two examples to help you determine your probable last frost and first freeze dates.

Example 1 (Last Frost). In the Spring 32° row, if you have "Apr 15" under the 50% column, that means you have a 50% chance of seeing frost on or before April 15th.

Example 2 (First Freeze). In the Fall 24° row, if you have "Dec 1" under the 90% column, that means you have a 90% chance of seeing 24 degrees on or after December 1st.

Empty cells indicate you have a less than 10% chance of ever seeing that temperature.

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