Weather
Chicago, IL Weather Oct. 20: Visibility May Drop to Near Zero This Morning
Chicago, IL – Drivers across portions of northeastern Illinois and northwestern Indiana could encounter dangerous visibility conditions early Tuesday, October 20, as locally dense fog develops across
By Jenna Hartley · 2026-10-20T08:31:12.919Z
Chicago, IL – Drivers across portions of northeastern Illinois and northwestern Indiana could encounter dangerous visibility conditions early Tuesday, October 20, as locally dense fog develops across the Chicago metropolitan area. Visibility could drop to nearly zero in isolated locations, potentially slowing the morning commute.
According to the National Weather Service in Chicago, locally dense fog is expected through the early morning hours, with visibility dropping to one quarter mile or less in some areas.
The greatest concern is sudden changes in visibility , particularly for motorists traveling through locations where fog becomes unusually thick.
The Weather Service's forecast map identifies portions of northeastern Illinois and extreme northwestern Indiana as areas where patchy fog or more concentrated fog could develop.
Communities around Chicago, Aurora, Joliet, Elgin and Waukegan, along with portions of northwest Indiana near Valparaiso, should remain alert for rapidly changing conditions.
However, forecasters emphasize that fog will not be widespread, meaning some neighborhoods could experience relatively clear conditions while nearby areas encounter significantly reduced visibility.
Morning commuters may experience slower travel , especially along highways and local roads where fog limits the ability to see vehicles, intersections and changing traffic conditions.
Motorists traveling on major regional routes, including I 90, I 94, I 80 and I 294, should be prepared for localized visibility reductions where fog develops.
The National Weather Service recommends using low beam headlights, maintaining additional following distance and remaining alert for sudden changes in visibility.
High beam headlights should be avoided because they can reflect off fog and further reduce visibility.
Conditions are expected to improve shortly after sunrise.
Forecasters anticipate fog will dissipate quickly within one to two hours after sunrise, with the weather graphic valid through 8 a.m. CDT Tuesday.
Residents heading to work or school should allow extra travel time if dense fog develops along their routes.