And with the wind, it felt even colder- in some cases below zero. ABC7 meteorologist Tracy Butler said, "We haven't been this cold since mid-February. We are trying to get used to it all over again."
Along with the cold blast comes more snow, especially in Indiana and Michigan. A lake-effect snow warning is in effect until noon Tuesday for LaPorte Co, Ind., and Berrien County, Mich. Flurries were also spotted near O'Hare Airport and Arlington Heights Monday morning.
The city is working to make sure that those who are most vulnerable to the cold weather are not forgotten.
With the unseasonably chilly weather making early December feel more like January, the warming center at the Garfield Community Center saw a steady stream of people looking to escape the cold. City officials say there are still plenty of beds at homeless shelters. They are encouraging the public to notify them about anyone who needs help.
"We really asked the citizens of Chicago to be our eyes and ears in terms of well-being checks, and call us at any time and we will send somebody out to check on that person," said Commissioner Mary Ellen Caron of the Department of Family and Support Services.
Residents can call 311 to request a well-being check.
Those who venture outdoors are advised to bundle up, something Matt Klingler takes seriously. In his fourth year as a doorman for the Hard Rock Hotel, he's already dressing like it is the middle of winter.
"I like to keep track of the weather reports. I'm pretty religious about it, you know, every day throughout the day, seeing what's coming, being prepared because when it catches you unaware, that's the worst," said Klinger.
Some tourists chose to have fun outside, despite the cold.
"This is a good time for both of us to get out and it is not the busiest time for our jobs, so we came here even though it's freezing," said tourist Nicole Drake who was skating at Millennium Park's ice skating rink.
"I was hoping to take a taxi but she decided she would like to walk, so we're walking," said Caleb Martin, Drake's friend.
We all know that summer in Chicago brings out the tourists, but December? One couple from the south of France came here anyway, and if the cold is a shock to their system, you wouldn't know it.
"I have seen Internet, and Internet says ... Chicago, snow, snow, snow and very cold. I don't care," said Nelly Carroux, tourist from France.
UIC student Yinka Ayodele, who is originally from Africa, shivered in the cold as she crossed the street Monday.
"Usually, I get to leave, I see my family in Nigeria, so that nice," said Ayodele.
Officials reminded residents to make sure their pipes don't freeze by wrapping them in insulation and keeping a faucet dripping. Insurance agent Bill Klinowski sees hundreds of claims for broken pipes every winter.
"Prevention is always the best. Just wrap the pipes and keep them warm," said Klinowski.
The cold is also tough on pets who may wear a coat all the time but still should not be left outside in the cold for long periods of time.
"They are not necessarily prepared for spending long periods of time outdoors. So it's quite similar to how we experience the cold," said Dr. Charley Abernathy, Anti-Cruelty Society.
Authorities say two homeless men, both found outdoors in Joliet, may have died from hypothermia.