The snow is continuing to fall and forecasters say some northern Illinois communities could get another eight inches of fluffy lake effect snow.
The National Weather Service in Romeoville says Thursday's lake effect snow could extend as far west as Joliet.
Chicago is expected to get another 4 to 6 inches, although small pockets could receive up to eight inches.
Forecasters say some areas of northern Illinois have already received more than 11 inches of snow from the storm system. By midnight, O'Hare International Airport received more than 5 inches of snow.
In central Illinois, accumulations were about three inches Wednesday, but another 2 to 4 inches were expected to fall Thursday. Southwestern Illinois could get five inches.
According to FlightStats.com, about 165 flights have been canceled at O'Hare.
Commuters will need to exercise caution if they travel in Cook and Lake counties today, based on a National Weather Service warning.
Already a foot of snow has touched down in Lake County. The snow squalls result in highly variable accumulations and nearly zero visibility in some areas, creating hazardous travel conditions, officials said.
Isolated areas near Lake Michigan have already received more than 12 inches of snow this morning. Lake Villa has recorded 12-inches of snow since Wednesday, Mundelein has 15.5-inches, while Buffalo Grove has 15-inches, the Community Collaborative Rain, Hail and Snow Network has recorded.
Another 3-inches to 6-inches of snow is expected in areas that are in a lake effect snow warning area in Lake and Cook counties.
Because of the heavy snowfall, numerous spinouts are being recorded throughout Lake and Cook county. People should use extreme caution when driving Thursday.
Officials from Chicago Department of Aviation have announced more that 600 flights have been canceled at O'Hare International Airport and Midway Airport. Delays delays are averaging about an hour.
Because the snow has persisted longer and heavier than originally forecast, Illinois Department of Transportation crews planned to work through the evening in an effort to keep roads clear and passable in Lake, McHenry, Cook, Kane and DuPage counties, said spokeswoman Paris Ervin. She said IDOT has been receiving salt deliveries to make sure enough is available to address the winter storm.
Carmen Iacullo, assistant to IDOT's regional engineer, said crews have been plowing and salting about 360 routes in the six-county northeastern Illinois area since 2 p.m. Tuesday.
"Breakdowns could be an issue," he said.
Kevin Kerrigan, who directs snowplowing operations as the Lake County Division of Transportation's road maintenance engineer, said crews have been working in 12-hour shifts. He said all 25 plows have been on the roadways.
"The last few weeks, we've had quite a few callouts," Kerrigan said. "They're ready for a break."
While suburban drivers may not be thrilled about the snow, others are not complaining.
"I actually do enjoy it (snow)," Butch Olanosa said as he used an old snowblower on the sidewalk in front of his Batavia home Wednesday. "As long as I have these (earbuds)."
Ryan Courtney had to do more than clear snow at home. He drew the short straw having to work New Year's Day at Go! Calendars Games and Toys at The Arboretum in South Barrington.
"I had to shovel my way in through the packed ice by the doorway when I opened this morning at 10 a.m.," he said. "I'm shoveling the walk now to make sure nobody slips."
As of late Wednesday afternoon, some of the heaviest snow in the suburbs was recorded in Lake County, according to the weather service. Mundelein stood at 7 inches and Beach Park, to the east, at 7.4 inches. Towns across the Northwest suburbs received anywhere from four to five inches of snowfall, which restarted shortly after at 6 a.m. Wednesday, said weather service meteorologist Ben Deubelveiss.
While not the coldest December on record for the Chicago area, the average temperature for the month was 23.4 degrees -- 4.3 degrees below normal. The coldest the area has seen was December 1983, when the average temperature for the month was 14.3 degrees -- about 9 degrees colder on average.
"This was the 21st coldest December on record for Chicago," Deubelveiss said.
Last month's 14.2 inches of snow looks paltry compared to the December record of 33.3 inches in 1951. The December average is 8.2 inches, Deubelveiss said.
Temperatures will dip to zero overnight, then minus 10 degrees Monday and Tuesday nights, with highs right around zero degrees.
Below normal temps are expected to continue through this month, according to the National Weather Service's Climate Prediction Center. The normal high for January is around 31 or 32 degrees, while the normal low is about 16 or 17 degrees.
• Daily Herald staff writers Bob Chwedyk, John Starks and Mick Zawislak, and The Associated Press, contributed to this report.