An American Airlines Boeing 787-9 Dreamliner approaches Miami International Airport in this December 10, 2021, file photo. (Photo by Joe Raedle/Getty Images)
CNN  — 

Thunderstorms and low clouds over the East Coast are complicating air travel as many Americans are heading to airports during the busy spring break season.

Thousands of flights are delayed, with some delays stretching up to two hours, according to Federal Aviation Administration data.

By 4:15 p.m. on Thursday, more than 4,500 flights had been delayed, including more than 700 on Southwest, more than 560 on Delta, more than 370 on United and more than 560 on American, according flight tracking data from FlightAware.

Thunderstorms and clouds in the New York area caused air traffic controllers to halt departing flights bound for the New York’s LaGuardia Airport, according to the FAA. Delays at John F. Kennedy International Airport stretched over an hour and a half and were approaching that mark Thursday afternoon at nearby Newark Liberty International Airport.

Storms also affected air travel in Florida, according to the FAA. Delays ranged from 15 to 45 minutes in Orlando, Miami and Tampa on Thursday afternoon.

On Wednesday, more than 5,700 flights within, into or out of the United States were delayed, according to FlightAware.

Flight delays also hit travelers over the weekend during the busy spring break travel season.

More than half of Saturday flights on Southwest Airlines were either canceled or delayed because of “an intermittent technology issue, as well as ongoing weather challenges,” according to a tweet Saturday night from the airline.

According to FlightAware, 35% of Spirit Airlines’ flights, as well as 33% of JetBlue’s flights and 10% of Southwest’s flights were canceled on Sunday.

Top image: An American Airlines Boeing 787-9 Dreamliner approaches Miami International Airport in December 2021. (Photo by Joe Raedle/Getty Images)

CNN’s Andy Rose contributed to this report.