Illinois First Fall Frost (Occurrence of 32ºF)

The average date of the first fall occurrence of 32ºF ranges from October 21 in southwestern Illinois to October 7 in northern Illinois. The actual date can vary from year to year. It is interesting to note that the date is about a week later along Lake Michigan. The combination of a relatively warm body of water and the urban heat island effect may be the cause for this slight delay.

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