A staffing shortage is a main factor behind hundreds of American Airlines cancellations over the past few days.
As of 12:30 p.m. EDT, 134 American flights had been canceled Monday.
Cancellations topped 100 on Sunday and Saturday as well.
On Sunday, American said it would cancel around 1 percent of its flights in July.
The airline said unprecedented weather has caused multi-hour delays over the past few weeks, disrupting flight and crew working hours.
American also said it is dealing with labor shortages at some of its hub airports.
The cancellations reflect the stress a sharp increase in air travel demand has put on airlines.
According to the U.S. Transportation Security Administration, nearly 50 million airport passengers were registered in May. That’s up 19 percent from April.
Travelers are on pace to beat May’s numbers in June.