Coldest air of the season arrives today; Frost Advisory western sections tonight
A Frost Advisory is in effect for western counties of the Chicago area from 3AM to 8AM CDT later this Friday night and early Saturday morning for Winnebago, Boone, McHenry, Ogle, Lee, DeKalb and Kane Counties (blue-shaded counties on the headlined map), calling for temperatures to drop into the low to mid-30s causing frost to form along and west of the Fox River Valley.
Affected cities will include Rockford, Belvidere, Woodstock, Oregon, Dixon, DeKalb, Aurora and Elgin. Sensitive outdoor plants may be killed, if left unprotected. This frost is a little earlier than normal – the normal first frost in that portion of our area occurs around the second week in October.
The coldest air mass in over 4 months will spread over northern Illinois into northwest Indiana behind a cold front that will move through the area from the northwest this morning. Cloudiness will be slow to depart, even though the front will move off to the east and south today with even a few light showers possible this afternoon. Clearing skies and diminishing winds are expected from west to east overnight with the coldest air settling in across the sections under the Frost Advisory.