Over 500 flights were canceled at Chicago airports on Saturday morning as a winter storm bringing up to 10 inches of snow moves into the area.

After snowy weekend, Chicago expected to receive up to another four inches of snow on Monday during evening rush hour.

After a series of snowstorms barreled across the Plains and Great Lakes regions, millions across the Northeast are under winter weather advisories.

As of 4:30 p.m. EST, around 7,800 flights were delayed in the U.S. and another 670 canceled, according to online tracker FlightAware. Chicago O’Hare International Airport faced the heaviest impacts, with 642 delayed outbound flights delayed and 118 canceled.

A winter storm is hitting the Midwest with snow and wintry conditions, causing travel issues for many who were looking to get home following Thanksgiving. At least 450 flights had been canceled around the United States as of 7 a.m. ET, with the biggest impacts at Chicago's O’Hare Airport, according to FlightAware, a flight-data tracker.

Transportation Security Administration officials said Sunday was expected to be one of the biggest travel days in the history of the agency.

O'Hare saw 8.4 inches of snow on Saturday, making it the snowiest November day in Chicago's recorded history, according to the NWS. Wadsworth saw 11 inches of snow; Hoffman Estates, Palatine, Skokie and Valparaiso, Indiana had snow totals near 10 inches.

The NWS warned that travelers should consider delaying travel unless it's "absolutely necessary," with driving expected to be very difficult to impossible.