The warnings from government officials were stern: stay inside if you can, limit your time outside and don't drive unless absolutely necessary.
Chicago's O'Hare International Airport recorded -15 degrees at 7 a.m. Monday, breaking existing Jan. 6 low set in 1894 and tied in 1988. By 8:30 a.m., the official Chicago temperature had dipped another degree, to -16.
With the wind chill factored in, Monday's temperatures were in the -40 to -50 degree range and even lower across the Fox Valley. By midday, the lowest recorded wind chill was in Aurora, at -47 degrees. DuPage and Porter recorded -46 degrees and O'Hare reported -42 degrees.
A Wind Chill Warning that began at 6 p.m. Sunday was scheduled to remain in effect until noon Tuesday.
The area avoided setting a new all-time record low high temperature, with -2 degrees recorded at 12:03 a.m. That was a record for the day, breaking the old recorded low maximum of -1 set in 1912. The last time Chicago recorded a high temperature below zero was Jan. 15, 2009. The all-time lowest high temp was -11 on Jan. 18, 1994, and Dec. 24, 1983.
The chill was expected to persist Tuesday with negative air temperatures to kick off the day, only warming to a high of 5 degrees in the afternoon. Low temps could dip to -15, and wind chill values will plunge to -40.
Aviation officials said airlines proactively canceled more than 1,600 flights at O'Hare for the day. The delays affecting those flights that were coming or going were averaging about 40 minutes, they said. Another 85 flights were proactively canceled at Midway International Airport, and delays there were averaging about 20 minutes.
Customers were advised to check with their airline before heading to the airport.
Monday's cancellations were on top of the more than 1,300 flights that were canceled Sunday at O'Hare because crews reported icing issues. Midway had more than 200 flights canceled on Sunday.
Several Northwest Indiana counties declared states of emergency due to extreme winter weather conditions in the area. Sections of Interstate 65 and Interstate 94 were closed Sunday night to all traffic due to impassable sections and ramps, officials said.
The Chicago Transit Authority said the weather conditions were causing problems with the switchers on several lines. TransitChicago.com maintains up-to-date system status and alerts.
The bitter temperatures follow several days of snowfall. As of 6 p.m. Sunday, the NWS reported 11.7 inches of snow at O'Hare, 9.6" at Midway and 11.2" at the NWS office in Romeoville. The snow that fell Sunday at O'Hare -- 8.7" -- exceeded the old recorded daily snow maximum of 6.2" set in 2005.
The Chicago Department of Streets and Sanitation deployed more than 280 salt spreaders and snow plows as the system moved into the area. Illinois Tollway officials said they mobilized 182 snowplows.
Illinois State Police said they handled nearly two dozen crashes Sunday morning and responded to several cars in ditches statewide. Officials warned drivers that road conditions were expected to "deteriorate" Sunday night and into Monday morning.
The Kane County Sheriff's Office warned residents that road conditions were "deteriorating rapidly" Sunday.
"The higher winds are starting to cause roads to drift over and become impassable," Lt. Pat Gengler said in a statement.
Route 38 between Elburn and Maple Park was closed Sunday afternoon due to drifting snow causing the roads to be impassable, Gengler said.
The deputy commissioner for Preparedness and Emergency Response at the city's Department of Public Health urged residents to avoid unnecessary trips outside, work slowly and take frequent breaks when shoveling snow, don’t try to lift more snow than you can handle, and wear several layers.
"The current snowfall and extreme cold temperatures expected next week pose significant health risks to residents," Dr. Suzet McKinney said Thursday.
Be sure to cover your face, ears and hands, McKinney said.