Hundreds of flights have been canceled after a snowstorm struck on one of the busiest travel weekends of the year

• Hundreds of flights have been canceled on Sunday after a snowstorm hit the Midwest.
• Chicago's O'Hare airport has seen the most cancellations and delays.
• About 1,500 flights were canceled in Chicago on Saturday when the storm first hit.

Hundreds of flights were canceled or delayed across the United States on Sunday after a winter storm battered the Midwest over the weekend.

About 240 flights into or out of Chicago's O'Hare International Airport were canceled as of 11 a.m. ET on Sunday. Another seven were canceled at Midway Airport, according to flight-tracking website FlightAware. Hundreds of others were delayed in the Chicago area, one of the country's busiest flight hubs.

Another 1,500 flights were canceled on Saturday as heavy snow and strong winds swept across the Chicago region, according to FlightAware data.

The winter storm — and the subsequent flight cancellations and delays — come as Americans travel following the Thanksgiving holiday, typically some of the busiest travel days of the year.

The Transportation Security Administration had predicted that Sunday would be one of the busiest days in its history.

The agency said it would likely screen over 17.8 million people from November 25 to December 2, including more than 3 million on Sunday alone.

In an update, the National Weather Service said a period of "accumulating snow" was expected from Monday afternoon into Monday night in the Chicago region.

The agency said this "may produce hazardous travel conditions for the Monday afternoon commute and potentially lingering impacts for the Tuesday morning commute."

Another winter storm could hit New England and the Mid-Atlantic in the coming days, the Weather Prediction Center added.