American Airlines canceled more than 600 flights on Sunday, which is over 12% of its operations for the day.
Since Friday, more than 1,500 American Airlines flights have been canceled due to weather issues and staffing shortages, CNN reported.
"With additional weather throughout the system, our staffing begins to run tight as crew members end up out of their regular flight sequences," the airline told CNN in a statement on Saturday.
American said that arrival capacity was significantly reduced from severe winds for two days in Dallas-Fort Worth, which is its largest hub.
According to flight tracking website FlightAware, American canceled 543 flights on Saturday and 342 on Friday.
Following buyouts and early retirements of airline employees during the reduced air travel amidst the COVID-19 pandemic in 2020, the airline expects the return of more flight crews during the holiday season, as 1,800 flight attendants are returning from leave Monday, with more by Dec. 1. American also said it will increase hiring in the fourth quarter, according to CNN.