CHICAGO (CBS) — The return of subzero temperatures early Thursday could mean more problems for people who ride Metra, which was warning commuters to allow for extra travel time to get where they’re going.

A wind chill advisory was in effect for the Chicago area until noon on Thursday.

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The frigid blast of weather likely will create delays on some Metra trains.

“Please allow extra travel time to assure your safe passage to and from your destination. We regret any unanticipated weather related delays that you may experience and appreciate your patience,” Metra warned on its website. “As always, we will make every reasonable effort to assure your timely and comfortable commute. Unfortunately, weather conditions beyond our control will create unanticipated delays or service disruptions. Depending on the severity of conditions in specific areas, your train may experience delays. Metra will continue to utilize all possible measures available to combat extraordinary weather conditions.”

Frigid weather led to several delays and cancellations along a number of Metra lines last week, leaving many trains extremely overcrowded. In many cases, rail switches became jammed with ice, and it took crews a long time to clear them. In some cases, trains were delayed up to 2 ½ hours. Dozens of other trains were cancelled altogether.

Metra officials said better communication during this latest bout of frigid temperatures should help avoid confusion about any travel issues, but they can’t prevent delays caused by the extreme cold.

As of 7 a.m. , the only travel issue Metra was reporting was along the Milwaukee District/West Line, where inbound train #2212, scheduled to leave Roselle at 6:54 a.m., was cancelled due to mechanical problems. Other trains will accommodate passengers who normally use that train.

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Though, with no snow or other precipitation in the forecast for Thursday, switching problems should be minimized, and there should not be as many problems for Metra as last week.

CBS 2 Meteorologist Mary Kay Kleist reports, with a high temperature of only about 9 degrees on Thursday, wind chills will be below zero all day. Northwest winds gusting up to 30 mph will create dangerously cold wind chills as low as 20 to 25 below zero.

Those dangerous wind chills also create a risk of frostbite and hypothermia, so people should avoid going outside unless it’s necessary, and cover any exposed skin.

Temperatures plunged to 2 below zero at O’Hare International Airport overnight, with wind chills as low as 22 below. In far west suburban DeKalb, the wind chill reached as low as 29 below.

It could get even colder Thursday night. The National Weather Service also has issued a wind chill advisory from 6 p.m. Thursday until 10 a.m. Friday.

The low temperature in Chicago is expected to be about 6 below zero overnight, with wind chills up to 30 below zero.

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The weekend will bring a few days’ respite from the extreme cold, as high temperatures will climb into the mid-20s on Friday, Saturday and Sunday, before plunging back into the single digits on Monday.