Frost Free Dates

The average date of the last frost in Central Illinois is April 15. This doesn't mean it is a frost-free date. There is a 50 percent or less chance of frost on this date. The odds of a frost drop an additional 10 percent for each week past this date.

In central Illinois, the FROST FREE date is May 12. Add approximately 1 week for each 100-120 miles north of Springfield and subtract 1 week for each 100-120 miles south of Springfield.