Aside from the center of Chicago, a killing frost and possible freezing temperatures are expected to occur across northeast Illinois and northwest Indiana late tonight and early Saturday morning. As high pressure builds into our area from the northwest, clouds are expected to thin-out tonight and winds diminish, allowing temperatures to fall into the 30s most areas and possibly upper 20s at locations further inland, away from the core of Chicago.

The Chicago National Weather Service has issued a Freeze Watch from 1AM to 9AM Saturday morning for most of the area away from the city proper with a widespread frost likely (light-blue shaded area on the headlined map and the map below). A Frost Advisory from 1AM to 9AM is in effect closer-in (darker blue-shaded area on map includes Du Page County, portions of Cook County and also Lake and Porter Counties in NW Indiana). Note a Freeze Warning from 1AM to 9AM is in effect for adjoining areas of southern Wisconsin and western Illinois (purple-shaded areas).