CHICAGO — After 37 hours of subzero temperatures, it finally hit zero degrees Tuesday afternoon.
But it's still pretty cold.
"The zero is a number. Something that catches our eyes," said Matt Friedlein of the National Weather Service. "It's still cold out."
After below-freezing temperatures broke city records on Monday, forecasters said wind chills are likely to keep the air feeling frigid throughout the day Tuesday even as actual temperatures rise.
A polar vortex, which is an area of upper-level, low-pressure wind that generally stays near the North Pole but occasionally turns southward, ushered in record-low temperatures Monday, National Weather Service meteorologist Andrew Krein said.
A temperature of 10 degrees below zero was recorded at O'Hare Airport Tuesday, Krein said. Wind chills are likely to remain near 30 degrees below zero, Krein said.
The temperature turned zero degrees in Chicago at 1 p.m., according to Friedlein.
Elsewhere in the Chicago area, temperatures could reach a high of about 8 degrees, according to the weather service.
Commuters faced several obstacles Tuesday morning, including canceled Metra trains, multiple expressway crashes and CTA delays due to the freezing conditions. Bike-share system Divvy also announced it would stay closed for business.
But unlike Monday, Krein said the city is unlikely to break more weather records.
Tuesday was not the coldest Jan. 7 in Chicago history. In 1912, the city hit a low of 16 degrees below zero, Friedlein said.
On Monday, meteorologists measured 16 degrees below zero at O'Hare, breaking the low temperature record for Jan. 6 of 14 degrees below zero set in 1884 and 1988.
The city hadn't seen daytime temperatures that cold in two decades, the weather service said. As temperatures plummeted, many used the nickname and hashtag "Chiberia" to describe the climate.
The city opened warming centers for extended hours, which will continue Tuesday from 9 a.m. to 8 p.m.
Chicago Public Schools called off classes for a second day. Scores of other Chicago area schools were also closed for the day.
Those who hope to escape the city Tuesday might have a difficult time, as more than 1,000 flights were canceled at O'Hare, and more than 180 flights have been canceled at Midway, according to the city's Aviation Department.
Flights at O'Hare reported delays averaging about 20 mins, while a handful of flights at Midway suffered 45-minute delays.
It was so cold that even the local polar bear at Lincoln Park Zoo, who hasn't developed the layer of blubber she would have in the wild, had to stay inside.
According to the city's Plow Tracker, the Department of Streets and Sanitation sent out a full fleet of more than 280 snow plows and salt spreaders to clean up after some areas saw nearly a foot of snow from Saturday to Sunday.
And Gov. Pat Quinn issued a statewide disaster declaration, which activated the Illinois National Guard to assist local responders.
Temperatures are expected to warm to a high of about 15 degrees on Wednesday, though wind chills could make the air feel like 6 degrees below zero. There's about a 20 percent chance for snow Wednesday and Thursday.