With temperatures dropping far below zero, officials said having a place to stay can be the difference between life and death.
That's why municipalities, libraries, businesses and other organizations are opening their doors to people in need during the freezing winter days.
For example, Naperville has set up warming shelters at the municipal center, 400 S. Eagle St.; the three library locations, 200 W. Jefferson Ave., 2035 S. Naper Blvd. and 3015 Cedar Glade Drive; and the Alfred Rubin Riverwalk Community Center, 305 W. Jackson Ave. The Des Plaines, O'Hare and Lake Forest Oases along the tollway will also serve as warming locations.
A full list of warming locations by ZIP code can be found at keepwarm.illinois.gov.
"Any prolonged exposure to extreme cold can be life-threatening," said Illinois Department of Public Health Director Dr. LaMar Hasbrouck. "We want people to get to these warming centers, dress appropriately, learn the warning signs and seek help if needed."
People can also call their local village or city government to find out where warming shelters have been set up within their community.
Hypothermia, or a drop in body temperature to 95 degrees Fahrenheit or less, can be fatal if not treated quickly, he said. The condition can develop as quickly as within 20 minutes outside in the cold without proper attire, but also can set in over several days in mildly cold indoor temperatures. That's why this cold snap is not a time to cut back on the heat, Hasbrouck said.
Signs of hypothermia include forgetfulness, drowsiness, slurred speech, change in appearance, weak pulse, slow heartbeat, shallow breathing or coma, he said.
If you have to go outside, Hasbrouck suggested covering the most at-risk areas such as fingers, toes, chin, nose and ears to avoid frost bite. Frostbitten skin will appear white and stiff and feel numb rather than painful, he said.
Frost bite and hypothermia should not be treated by instantly jumping in a very hot shower however, because the quick temperature change could also cause nerve or tissue damage, Hasbrouck said.
The cold weather is even more dangerous for infants and older adults who lose body heat faster than other populations.
"If you start shivering, that's your body's way of saying 'I'm too cold,'" he said.