According to flight tracking website FlightAware, 912 flights have been canceled so far on Sunday.
A total of 6,378 flights have been delayed in the United States.
Chicago O’Hare saw the most cancellations and delays on Sunday, with about 12% of flights canceled and more than 40% of flights delayed.
Chicago saw heavy rain Sunday, including a flash flood warning that was in place for parts of the afternoon for parts of Cook County.
Weekend of cancellations
A total of 657 flight cancellations and 7,267 delays were reported in, within or outside the United States on Saturday.
American Airlines canceled 4 percent of its flights and 24 percent of its Saturday flights were delayed, according to FlightAware.
United had 4% of its flights canceled and 23% delayed, followed by Delta with 2% canceled and 22% of its Saturday flights delayed, FlightAware notes.
41 percent of JetBlue flights and 36 percent of Southwest flights were also delayed Saturday, according to the website.