This week's snowfall is telling Chicagoans that winter has arrived. And continued subzero temperatures and wind chills as low as minus 30 degrees Tuesday and Wednesday should serve notice it's not leaving anytime soon.
"It looks to be pretty, pretty darn cold here, even for Chicago," said National Weather Service meteorologist Kevin Birk.
A winter weather advisory for dangerous travel conditions because of blowing snow and low visibility went into effect Monday evening and lasts until 6 a.m. Tuesday.
The snow was hitting the Chicago area Monday evening, and at times was expected to come down as fast as an inch or two per hour. Accumulations will range from 2 to 4 inches in north parts of the Chicago area, with accumulations of 3 to 6 inches possible in areas south of the city.
Roads in the south suburbs were becoming snow-covered, with Palos Park Police reporting near white-out conditions and the Illinois Department of Transportation reporting the most road problems in the south suburbs.
"We have a few (accidents) here and there," said Illinois State Police District Chicago Sgt. Dominick Falcone, whose district polices Chicago-area expressways. "At this point in time things are under control, but we are expecting it to get worse as time goes on."
Preparations were under way to combat the cold and snow on many fronts, including schools, transportation, warming shelters and even animal shelters. By a little before 9 p.m., Chicago had its full snow fleet of more than 280 plows deployed to main streets.
Air travel was also affected by the weather. O'Hare International Airport saw about 270 flights cancelled and more than 1,300 flight delyaed Monday, according to flighttracker.com. More than three dozen flights out of Midway Airport had been delayed as of Monday evening, according to the city's department of aviation.
Some O'Hare passengers reported hour-long delays. Just before midnight, Julie Crothers, a Chicago resident, said her plane had been sitting on the tarmac at O'Hare for more than an hour and half.
Crothers had one word to describe the experience: "Painful."
"I guess it makes you wonder what the airlines and airports are prepared for," Crothers said. "It's not even that much snow. What happens if there's a blizzard?"
Crothers' flight had experienced about an hour delay flying out of New York Monday evening. When the plane landed at O'Hare, the pilots told passengers they had to wait for a gate as outbound planes were being de-iced, she said.
"Even the pilots said it's inexcusable," Crothers said.
She said flight attendents handed out the rest of the food on the plane for free, and passengers were "pretty calm" for the most part.
Chicago Public Schools will remain open Tuesday, but Mayor Rahm Emanuel said at a Monday news conference that Wednesday is an open question.
"When you have both the snowfall as well as the temperature drop, we're going to be monitoring on a minute-by-minute basis as it relates to the weather, and make a decision with enough time for parents to both plan and prepare," he said.
Metra, whose customers last January endured dozens of weather-related cancellations and delays, to have personnel on duty through the night until Tuesday morning in preparation for the rush hour to help ensure that trains will run on time during the expected cold and dangerously blowing snow.
"We're taking all precautions," Metra Deputy Executive Director Peter Zwolfer said. "We're not taking any chances."
In addition to 24/7 staffing at key locations, such as major switching points, Metra will keep locomotive fuel tanks topped off and have new switch heaters and cold-air blowers on hand to keep equipment operating, Executive Director Don Orseno said.
Snow plows would also be deployed as needed overnight Monday into Tuesday morning to keep Chicago roads, area highways and the Illinois Tollway open, city and state officials said.
The city also announced plans to keep its warming centers open an extra three hours each evening, until 8 p.m. "during work weekdays when temperatures dip below 32 degrees," according to a news release.
Forecasters said it's unclear whether the coming months will come in as fiercely as did last winter - it ranks as the city's third-coldest on record - though there will likely be more single-digit high temperatures beyond this week.
As Monday dawned, wind chills as low as 32 below were recorded in Harvard, 23 below in Crystal Lake and 22 below in McHenry. Real temperatures as low as 11 below zero were recorded in McHenry County. Temperatures at O'Hare International Airport finally climbed above zero around noon.
The relatively brief burst of snow was brought by an Alberta clipper low-pressure storm system, according to the weather service. The system, which typically forms in Canada's Alberta province, will be followed by more blasts of Artic air Tuesday and Wednesday.
Chicagoans could see some respite by early next week, said weather service meteorologist Charles Mott said, with a predicted high temperature Sunday in the mid-20s.
Forecasts beyond the weekend are variable, but Birk said the area will probably see more blasts of cold air at some point, based on larger-scale weather patterns.
But until then, it could be a rough ride. Tuesday's forecast calls for high temperatures in the low to mid-teens with winds from 10 to 20 mph and gusts of up to 30 mph, according to the National Weather Service. Overnight low temperatures in the city could be around zero degrees and minus-3 to minus-7 in the suburbs, with wind chills as low as 30 below.
Monday's winter weather comes after the area already saw from 2 to 3 inches of snow Sunday. As of Sunday evening, 2.2 inches had fallen at O'Hare International Airport since midnight, according to the National Weather Service.
Monday's weather caused disruptions for air travel. O'Hare International Airport and Midway Airport reported delays, and about 230 flights out of O'Hare had been canceled as of 8:35 p.m. Monday according to the Chicago Department of Aviation, on top of similar cancellations Sunday. Airlines were reporting some delays at both airports Monday night, according to the Aviation Department.
Metra reported delays on many of its lines early in the morning, including the Union Pacific Northwest, Milwaukee District, Burlington Northern Sante Fe, Rock Island and Metra Electric.
No schools in the Chicago area were closed for the weather Monday, according to emergencyclosingcenter.com.
The weather service urged people to stay indoors if possible and to bundle up when going outside. The combination of such low temperatures and high winds means the wind chill could cause frostbite to exposed skin in just minutes, Birk said.
Last winter's frigid temps brought more than five times the usual number of frostbite cases to University of Chicago Medicine, according to spokesman John Easton. Frostbite -freezing of the skin and underlying tissues - happens when skin is exposed to cold-weather conditions, and can speed up quickly with subzero wind chills, according to the Mayo Clinic.
A total of 53 patients ages 2 to 84 were treated for frostbite between November and March, according to Easton. In the seven years before that, no winter had more than 7 patients admitted.
The cold means animal care workers make adjustments too.
On Monday, one of the city's biggest animal shelters, PAWS Chicago, "saved our first frostbitten cat of the year," said spokeswoman Sarah Ahlberg, who said the stray cat, Sunny, who suffered from frostbite on her ears, came to the shelter from the city's animal control department and will be treated at its medical center for frostbite on its ears.
For all its potential perils, this week's cold and snow are just life as usual for some Chicagoans.
"When I was a kid, we would get a couple of inches of snow, and it was like, 'Yeah, snow. It's kind of cold and everything.' But now it's like, 'Oh my God, it's Armageddon,'" said lifelong Chicagoan Patrick Boyle, who was shopping Monday for spray to keep his door locks from freezing. "It's nothing. It's cold, and it's snowing. So what? You live in Chicago, deal with it."
Mike Slomski, manager of Stauber's Hardware in North Center, where Boyle was shopping, took it a step further.
"The business side of me says, 'Let it snow.'"
Tribune reporters Richard Wronski, John Byrne, Stephanie K. Baer, Quinn Ford and Meredith Rodriguez contributed.