American Airlines has canceled more than 800 flights between Friday and Saturday, according to FlightAware.
Several cancellations were reported coast to coast from Charlotte, North Carolina to Los Angeles.
The company blamed the numerous cancellations on severe weather out of Dallas, Texas and staffing shortages.
"To make sure we are taking care of our customers and providing scheduling certainty for our crews, we have adjusted our operation for the last few days this month by proactively canceling some flights," Chief Operating Officer David Seymour said in a statement to FOX Television Stations Saturday. "We are taking this measure to minimize any inconvenience as much as possible."
"Most of the customers impacted by these changes are being rebooked the same day, and we apologize for having to make these changes," the statement continued.
The company said it expects to ramp up staffing within the coming months, with nearly 1,800 flight attendants returning from leave on Nov. 1. It also hopes to hire more than 600 additional flight attendants by the end of December.
The company added that it expects to hire 4,000 airport personnel by the end of the year.
The moves is the latest indication that leisure travel in the U.S. is recovering more quickly from the pandemic than airlines expected.
"Increasing customer demand and new routes starting later this year mean we need more flight attendants to operate the airline," Brady Byrnes, the airline’s vice president of flight service, told flight attendants in a memo over the summer.
Last year, American offered long-term leaves of absence to flight attendants and other employees to cut costs while it struggled with a steep drop in travel caused by the coronavirus outbreak. Other airlines did the same thing. Now they need people.
When the pandemic hit, the number of people flying in the U.S. plunged below 100,000 on some days, a level not seen in decades. This year, it has climbed from less than 700,000 a day in early February to 2 million a day in July.
American Airlines, Alaska Airlines and JetBlue are joining United Airlines in requiring employees to be vaccinated against COVID-19, as the Biden administration steps up pressure on major U.S. carriers to require the shots.
American Airlines CEO Doug Parker told employees that the airline is still working on details, but "it is clear that team members who choose to remain unvaccinated will not be able to work at American Airlines."
The pilot union at American recently estimated that 4,200 — or 30% — of the airline’s pilots are not vaccinated.
Airlines are large employers that fall under Biden’s sweeping order that companies with more than 100 workers require employees to be vaccinated or undergo weekly testing for the virus.
Employees can seek waivers from the vaccines on medical or religious grounds.
A group reportedly totaling hundreds of people including current and former American Airlines employees protested outside the company's Fort Worth, Texas, headquarters last week, over the carrier's decision to mandate that all employees get vaccinated for COVID-19 or lose their jobs.
A crowd of hundreds also gathered outside American's Fort Worth headquarters earlier this month on Oct. 7, after the company announced its workers would face being fired if they were not fully vaccinated by Nov. 24.
The Associated Press and FOX Business contributed to this report. This story was reported from Los Angeles.