UPDATE (7:09 a.m. Thursday, Jan. 23): The National Weather Service's wind chill advisory has been extended until 11 a.m. Friday, Jan. 24. Wind chills could reach 20 below to 30 below zero Thursday night.
According to the National Weather Service, "a strong arctic frontal boundary will arrive across northern Illinois late this afternoon and across northwest Indiana early this evening."
This frontal boundary will bring winds of 25 to 30 miles per hour and wind chill values of 20 to 25 degrees below zero tonight. Wind chill values could reach 30 below zero early Thursday, according to the National Weather Service.