Weather
Chicago, IL Tonight: Coldest Air Arrives Before Tuesday Oct 20
Chicago, IL – Residents heading outdoors late Monday night and early Tuesday morning should prepare for a chilly start as temperatures across the Chicago area drop into the low to mid 40s overnight, d
By Cole Barrett · 2026-10-19T18:59:13.688Z
Chicago, IL – Residents heading outdoors late Monday night and early Tuesday morning should prepare for a chilly start as temperatures across the Chicago area drop into the low to mid 40s overnight, despite an unusually pleasant stretch of October weather.
According to the National Weather Service in Chicago, temperatures are forecast to fall between 41 and 45 degrees overnight Monday, October 19, into Tuesday, October 20 , with some locations experiencing patchy fog.
The overnight forecast marks a noticeable contrast to the mild afternoon conditions expected throughout the remainder of the week.
For residents leaving home early Tuesday, particularly commuters, outdoor workers and students waiting at bus stops, a jacket or additional layer may be useful before temperatures begin climbing after sunrise.
Tuesday afternoon is expected to bring mostly sunny skies, with highs ranging from 67 to 72 degrees across the region. Areas closer to Lake Michigan may remain cooler, with temperatures in the mid 60s.
The warming trend continues Wednesday, October 21, when afternoon highs are expected to reach 68 to 73 degrees. Overnight temperatures heading into Thursday morning should remain slightly milder, generally between 45 and 48 degrees.
Thursday, October 22, will bring additional sunshine and highs between 68 and 74 degrees, followed by overnight lows of 46 to 49 degrees.
By Friday, October 23, partly cloudy skies are expected, with afternoon temperatures reaching 67 to 74 degrees.
The National Weather Service says the warm, dry and sunny pattern should continue through at least the end of the week.
While Chicago residents can expect chilly mornings, the extended forecast offers several opportunities to enjoy comfortable afternoon temperatures before colder late autumn conditions eventually return.