AUSTIN (KXAN) — Ahead of the busiest travel days of the year at Austin-Bergstrom International Airport, Southwest Airlines canceled dozens of flights that stretched into Monday.

On its Twitter account Saturday, Southwest Airlines said the cancelations are due to “air traffic control issues” and “disruptive weather” that led to widespread cancelations across the country, including Austin.

According to the Austin airport’s flight board, dozens of arrivals and departures at AUS were canceled as over the weekend. Some of those cancelations bled over into Monday, creating busy security checkpoints and long waits.

The cancelations come on the heels of Southwest Airlines officials requiring its employees to be vaccinated for COVID-19 by Dec. 8 “to continue employment with the airline.” The airline made that announcement Oct. 4.

In total, Southwest Airlines has canceled about 1,800 of its flights, 27% of its schedule, over the weekend. By Monday morning, 19 departure flights had been canceled. Other airlines that serve the regions the flights are in are reporting far fewer cancelations.

It was a fun weekend of travel, for Austin City Limits festival-goers coming into Austin, but now Katie Hickey and Peri Tehven are slowly coming down from cloud nine, stuck with a canceled flight.

“Went out and about last night after the festival, ended up being at a bar around 1 and got a text, ‘Hey your flight is canceled,’ no reason, no explanation, just canceled,” Hickey and Tehven said.

“I own a business in Denver,” Tehven said. “Tomorrow I had to get back. that’s why we chose an earlier flight.”

According to the ABIA public information officer Bryce Dubee, about 100 flights were canceled by Southwest.

“More importantly, that’s going to have an impact over the next few days is those passengers do get rebooked on their travel plans,” Dubee said. “If you’re going to be flying in the mornings… you’re going to want to give yourself at least a good two and a half, three hours to get through security.”

Hickey and Tehven were able to rebook their flights. They said they’re taking things for what they are, hoping to make it home safe on Monday.

“They’re trying their best,” Hickey said. “If we were meant to stay here an extra day, then shoot, I’m not going to complain about it too much.”

Social media helped fuel speculation that the cancelations were caused by Southwest Airlines staff members banding together for a nationwide “sick-out” as a protest of sorts due to the vaccine mandate. A Southwest spokesperson said that’s not the case.

We experienced weather challenges in our Florida airports at the beginning of the weekend, challenges that were compounded by unexpected air traffic control issues in the same region, triggering delays and prompting significant cancellations for us beginning Friday evening. We’ve continued diligent work throughout the weekend to reset our operation with a focus on getting aircraft and Crews repositioned to take care of our Customers.

With fewer frequencies between cities in our current schedule, recovering during operational challenges is more difficult and prolonged.

We’re working diligently to accommodate our Customers as quickly as possible, and we are grateful for their patience. We’re offering Customers added flexibility to explore self-service rebooking options on, where they can get updates on the status of their travel. We know the frustration flight cancellations are creating for our Customers and Employees and we apologize, and we again thank everyone for patience as we work first to be safe, and second to be as quick as possible in solving disrupted plans

Southwest Airlines spokeperson

The Federal Aviation Administration has yet to comment on the issue.

With the last day of ACL Fest on Sunday, a lot of concertgoers will need to catch flights through Monday at the airport. Officials say the anticipated amount of traffic through the airport could break records as people leave town.

Airport officials said Saturday when the cancelations began that people with flights through Southwest Airlines should check their flights during the day and contact the airline directly about any changes. They also stressed to people to show up at least 2.5 hours early for flights.