The National Weather Service issued a Frost Advisory for several counties across the Chicago area through Friday morning.
Winnebago, McHenry and Boone counties are all under the Frost Advisory which warns of temperatures falling into the 30s but still above freezing.
The alert takes effect beginning at 3 a.m. Friday morning and is scheduled to expire at 9 a.m. NBC Storm Team 5 said outdoor plants may be damaged or killed if left uncovered outside.
October began on a chilly note Thursday with temperatures in the 50s that are expected to continue throughout the next several days as a cold front crosses through the Midwest and brings with it unseasonably cool air and instability showers developing throughout the day.
Clouds and early morning lake showers will linger Friday morning in Northwest Indiana, but areas closer to Chicago should see partial sunshine with breezy and chilly conditions.