Thousands of flight delays and cancellations upended schedules over the busy Juneteenth and Father’s Day travel weekend – the latest sign of ongoing travel chaos as carriers contend with staffing shortages and bad weather.

A total of 921 within, into or out of the United States were canceled on Sunday, according to data from tracking service FlightAware. An additional 6,228 US flights were delayed.

Delta was forced to cancel 249 flights, or 8% of its total schedule for the day. American Airlines canceled 96 flights and United Airlines nixed 92 flights.

“A variety of factors continue to impact our operations, including challenges with air traffic control, weather and unscheduled absences in some work groups,” Delta said in a statement. “Canceling a flight is always our last resort, and we sincerely apologize to our customers for the inconvenience to their travel plans.”

The Post has reached out to the other airlines for further comment.

A massive wave of disruptions impacted trips over one of the busiest travel weekends, according to data from the Transportation Security Administration. More than 2.4 million people passed through TSA checkpoints at US airports last Friday alone – the most of any day this year.

Travel disruptions also occurred on Saturday, when more than 6,400 flights were delayed and 860 were canceled.

The chaotic travel conditions continued on Monday morning, with an additional 297 US flights canceled as of 10:35 a.m. ET. More than 1,000 planned US flights were delayed.

New York’s LaGuardia and JFK Airports are among those most impacted by Monday’s disruptions, according to FlightAware.

Similar troubles snarled air traffic over Memorial Day weekend and the winter holidays.

Flight cancellations aren’t limited to the United States. London’s Heathrow Airport asked carriers to cut flights slated for Monday due to a glitch with a baggage handling system, Bloomberg reported. London Gatwick airport also announced flight cancellations last week.

Elsewhere in Europe, Amsterdam’s Schiphol Airport slashed summer flights through July due to an expected shortage of necessary security personnel.

While travel figures still trail pre-pandemic levels, the industry has experienced a surge in demand in recent months – compounding the effects on airlines scrambling to manage a renewed volume of passengers.

Airlines are contending with shortages of pilots, flight attendants and other key staffers following a wave of layoffs and resignations during the COVID-19 pandemic. Carriers are also paying top dollar for fuel during a record surge in energy prices that has led some airlines to cut flights.

The flight disruptions have caught the attention of the Biden administration.

Treasury Secretary Pete Buttigieg said he has pushed for airlines to conduct “stress tests” for their summer schedules and warned the US could penalize carriers who fail to uphold federal consumer protection standards.

“That is happening to a lot of people, and that is exactly why we are paying close attention here to what can be done and how to make sure that the airlines are delivering,” Buttigieg said.

With Post wires