More than 1,300 flights inside or to the US UU., Delayed by bad weather

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(CNN) - In what is outlined as a historically busy travel day in the United States, airlines will serve about 3.1 million passengers this Sunday, according to the forecast of Airlines for America, a commercial airline organization.

A record 31.6 million passengers are expected to travel on American airlines during the Thanksgiving holiday period, 3.7% more than last year.

By midmorning, 1,300 flights inside or outside the United States had been delayed and almost 700 had been canceled, according to FlightAware.com. Travel affectations are expected to continue until Monday, the weather service said.

Delta Airlines announced climate exemptions for 16 cities in the Upper Midwest on Saturday and 22 cities in the Northeast for Sunday and Monday, including Boston airports and the New York area.

American Airlines issued exemptions for passengers traveling on Sunday and Monday on flights to and from the John F. Kennedy and LaGuardia airports in New York, as well as Newark and the airline's operations center in Philadelphia. Other cities in the American Airlines ad include Boston, Buffalo, Pittsburgh and Toronto, Canada.