Friday is expected to be this year's coldest day so far, with a wind chill advisory lasting until noon.

Thursday's high temperatures peaked at 18 degrees in the early morning, with area experiencing a steady decrease in temperatures throughout the day, said meteorologist Tim Gross of the National Weather Service.

Overnight temperatures were expected to fall below zero for the first time since Jan. 22, he said. Temperatures may drop to 4 below zero and, fueled by winds of 10 to 20 miles per hour, create a wind chill estimated to be as low as 25 degrees below zero.

Despite mostly sunny skies Friday, temperatures are expected to max out at 13 degrees. This pales in comparison to the record low of 21 degrees below zero set in 1996, yet it remains lower than the average highs of the low 30s for the end of January, Mr. Gross said.

The phenomenon of colder temperatures after a snowfall is commonly attributed to snow's high "albedo," the intensity at which something reflects light and radiation from the sun, Mr. Gross explained. This radiation is "bounced" back into the atmosphere rather than warming the earth, he added.

Once the snow melts sometime next week, temperatures are expected to return to normal, the meteorologist said.