Temperatures Tuesday morning were in the single digits, with a colder night in the forecast.
Click here to see school closings due to bitter cold temperatures
A Wind Chill Advisory is in effect through noon Wednesday for the entire Chicago metropolitan area.
FULL 7-DAY FORECAST
Several Metra lines, including North Central Service and Milwaukee District North reported issues with switching due to the cold. Trains on both Metra lines were operating delays up to 35 minutes due to switching problems.
Metra is using gas burners and other heating equipment to heat the rails and with arctic-like conditions expected in the morning they will leave train engines running overnight.
"Everything we can think of doing, we will do," said Metral spokesman Michael Gillis. "And we will try and make sure that your ride is safe, comfortable, warm and timely."
Overnight temperatures going into Wednesday morning are expected to be the coldest of the season, with temperatures going below zero and wind chills of -20.
The weather is particularly dangerous for the homeless men and women in the Chicago area.
"I need a heater for my tent," said Chris Gunion. "The one I had quit on me, and someone else gave me one and it didn't work. I've been without heat for almost a week now."
The 42-year-old is one of many trying to stay warm and alive as temperatures plunge. Lana Ake said conditions are bad for anyone outside, and it's going to get worse for her come nightfall.
"I've got two canisters for the whole week, of propane, and one is only good for four hours," she said.
As the freeze continues, there is concern about the dangers for unhoused people living outside, who could suffer frostbite or hypothermia.
"This is a health concern we are worried about every time the temperature starts to fall below 40 degrees Fahrenheit," said Dr. Stathis Poulakida, Cook County Health burn surgery director.
The National Weather Service warns the bitter cold can cause frostbite on exposed skin in as little as 30 minutes.
Chicago has activated six community warming centers which are open from 9 a.m. to 5 p.m.
-45 W. Wilson Ave
-4312 W. North Ave1140 W. 79th Street (79th/Racine Ave)
- 1140 W. 79th Street (79th/Racine Ave)
-8650 S. Commercial
-4314 S. Cottage Grove Ave
-10 S. Kedzie (Kedzie/Madison Ave)
The Garfield Center, at 10 S. Kedzie, is available 24/7. Libraries and park district sites are also available. To locate a center nearby, residents can call city services at 311 or visit 311.chicago.gov.
There are an additional 19 warming centers around Cook County, which can be found by clicking here.
The extreme cold also caused problems Tuesday for firefighters battling a fatal fire on the South Side. Frozen hydrants hampered efforts to put out the flames.
There are some steps you can take to keep your vehicle running and your house warm:
RELATED: Winter Wonder: What is 'pancake ice' on Lake Michigan, how does it form?
When it comes to your home, experts advise:
The Chicago Fire Department does not recommend using space heaters; however, if used, be sure they are UL certified and at least 3 feet from anything that can ignite. The use of a space heater in children's rooms should be monitored closely as children sometimes move them close to or into the bed with tragic results, officials said. If extension cords are used, they should be rated at 15 amps minimum and never put cords under carpet. With the added demand on furnaces and boilers, CFD also reminds residents they are required by ordinance to have working carbon monoxide detectors to protect against carbon monoxide leaks from a heating system that could be fatal over time, and to keep smoke detectors in working order.
Another big problem in the cold: busted pipes.
To prevent this from happening:
When it comes to protecting yourself from frostbite or hypothermia, use common sense, dress in layers and always wear a hat and gloves.