Memorial Day Weekend, AKA the unofficial start of summer, has kicked off with an uptick in flight cancellations. 

According to flight-tracking site FlightAware, there were over 1,600 flight cancellations as of Sunday at 11:40 p.m. There were over 1,500 cancellations on Saturday and 2,300 on Friday.

Delta Air Lines took a major hit with over 250 flights or 9% canceled on Saturday and over 160 flights or 6% canceled on Sunday. The airline’s base is Hartsfield-Jackson International Airport in Atlanta, which also had cancellations and delays. The Atlanta airport saw 5% of its flights canceled on Saturday and 19% of its flights delayed. On Sunday, 3% of flights experienced cancellations and 13% had delays.

In an email to The Associated Press, Delta states that the cancellations were due to bad weather and “air traffic control actions.” The airline states they would try to cancel flights during Memorial Day Weekend with at least a 24-hour notice. 

Delta Chief Customer Experience Officer, Allison Ausband says, “More than any time in our history, the various factors currently impacting our operation — weather and air traffic control, vendor staffing, increased COVID case rates contributing to higher-than-planned unscheduled absences in some work groups — are resulting in an operation that isn’t consistently up to the standards Delta has set for the industry in recent years.”

Newark Liberty International Airport in New Jersey also experienced dozens of delays and cancellations. 

Airlines are planning for an influx of travelers, but there are thousands fewer employees than before the pandemic. Airlines having fewer employees now than they did in 2019 is a contributing factor to flight cancellations. 

Inflation has led to increases in domestic airfare this summer. Flights are averaging at over $400 for roundtrip tickets, which is 24% higher than in summer 2019. 

Related: It’s Time We Realize That Black People Started Memorial Day