Over 100 million Americans under cold weather warnings as temperatures drop

More than 100 million Americans are under cold weather warnings, freeze or frost alerts, the National Weather Service said Thursday. Low temperatures have swept several major cities, bringing the first freezing temperatures and wind chills of the season.

The colder temperatures haven't set new records but are at least 15 degrees colder than normal across the East Coast — even as the western half of the country experiences warmer than normal climates. Most of the cold weather is due to a Canadian high-pressure system, which will maintain the colder temperatures through the end of the week.

In Chicago, the week has been marked by sub-freezing morning temperatures, the weather service said. Thursday's temperatures will only reach a high of 49 degrees but gradual warming is expected through Sunday. At the Chicago Rockford International Airport, forecasters recorded the first snow flurries of the season, which are not expected to turn into a storm.