The city responded by opening several warming centers and conducting well-being checks on the sick and elderly.
Authorities were warning Chicago area residents to just stay inside Sunday.
Like a winter ghost rising from the street, Sunday's brutal wind chill was somewhat visible throughout the Chicago area because of winds and leftover snow.
"The wind chill is humongous. If you don't have on the right clothes, it'll carry you away," Tommy Dorn told ABC7 Chicago.
Sunday, the city activated the Office of Emergency Management and Communications "Joint Operation Center," allowing officials from several city departments to coordinate efforts to fight the cold and keep residents safe.
"Don't let common sense become uncommon in this season. If you don't have to go outside, stay in. If you do have to go outside, make those trips as short as possible," said Dr. Terry Mason, commissioner for the Dept. of Public Health.
Many people who were brave enough to go outside Sunday afternoon had some shoveling and pushing to do before they could drive anywhere. And although many side streets have been salted, many of them were still in rough shape. Officials say that's because there hasn't been much traffic on those streets.
"What activates salt is traffic and friction. That's why you see the main streets in good shape, but the side streets, you'll see very little pavement," said Mike Picardi, commissioner for the Dept. of Streets and Sanitation.
While driving was more difficult Sunday, city officials were also concerned about those who may have lost heat in their homes. Authorities are asking residents to look out for one another, like one woman, Josephine Green, who regularly checks in on her 96-year-old neighbor who lives in the apartment below her.
"I check on him all the time...I still go and check on him, feed him, see if he needs anything from the store," she said.
The Department of Human Services (DHS) was conducting its own well-being checks Sunday, also offering free rides to warming centers.
Entire families need such assistance Sunday.
"The warming center is beautiful. It's a blessing," one person told ABC7 Chicago.
The DHS has workers on the streets looking for Chicago's homeless people, but they are asking for the public's help. If you see someone who may need assistance, please call the city's non-emergency phone number, 3-1-1.
In northwest suburban Huntley, drivers had to deal with the cold as well as blowing snow Sunday. A blizzard warning is in effect for several Illinois counties because of the strong winds that are kicking up snow and causing reduced visibility.
As for air travel, the Department of Aviation says O'Hare had 150 flight cancellations Sunday but only minor delays. Only a few problems were reported at Midway airport because of the weather.