A report from the internet travel site milecards.com sorted through 10 years of data to find Newark International Airport tops a new ranking of the nation’s airports with the worst on-time performance during the busy summer travel months, with an average of 66.5 percent of flights operating on schedule.

New York’s LaGuardia Airport had the second worst on-time performance, while John F. Kennedy International Airport was fourth on the list. San Francisco International Airport has the third fewest on-time arrivals among U.S. airports.

The Port Authority of New York and New Jersey, which operates Newark, LaGuardia and Kennedy airports, said it’s been working with the Federal Aviation Administration on putting NextGen in place, a new air traffic control system designed to reduce delays.

“New York area airports came at the bottom of the list consistently for that entire 10-year period,” said Brian Karimzad, director, milecards.com. “Summer is actually one of the worst times of the year to be flying when it comes to delays, in fact at Kennedy and LaGuardia you’ll have more delays in the summer than you’ll find during the dead of winter.”

The report, drawn from U.S. Department of Transportation data on the summer travel period 2007–2016, shows most U.S. airports have worse delays in the summer than the winter. June is the worst month for summer air travel delays. The rankings were based on arrivals, time spent taxiing and time waiting to get to the gate once a plane lands.

Kahului International Airport and Honolulu International Airport had the best on-time performance for summer travel, with 88 percent and 86.5 percent of flights arriving on time, respectively. Summer is considered a low season for Hawai’i travel.

Other airports with excellent on-time performance for summer travel include Salt Lake City International Airport, Orange County International Airport and Phoenix/Sky Harbor International Airport.