ARLINGTON, VA - JULY 11: A traveler walks past American Airlines planes gated at Ronald Regan Washington National Airport on July 11, 2022 in Arlington, Virginia. Staffing shortages, the COVID-19 pandemic and other issues have led to historic levels of disruptions in U.S. air travel. (Photo by Nathan Howard/Getty Images)
CNN  — 

Airlines and passengers are having the worst day for flight cancellations in a week because of thunderstorms bearing down on East Coast hubs.

FlightAware data showed 544 cancellations nationwide as of 7:50 p.m. ET Tuesday.

In the New York area, 9% of flights at LaGuardia International Airport had been canceled and 8% at Newark Liberty International Airport. At Washington’s Reagan National Airport, 11% of flights had been canceled.

The Federal Aviation Administration imposed a ground delay program late Tuesday afternoon for flights bound for Newark and LaGuardia. The FAA was also delaying some outbound flights still on the ground.

Severe storms moving through the the Northeast and Mid-Atlantic are expected to continue into the evening, according to CNN’s Weather team. Severe thunderstorm watches stretch from Virginia to Maine and are in effect through 10 p.m. ET.

“Weather conditions have caused LGA Airport flight disruptions,” said a Tuesday afternoon tweet from LaGuardia Airport’s official Twitter account. “Check with your airline to determine the status of your flight.”

Staffing pressure

Short-staffed airlines are under pressure from Transportation Secretary Pete Buttigieg to cancel fewer flights.

Weather disruptions are a regular feature of summer travel, but increased demand, airline staffing shortages and air traffic controller staffing issues have been adding to recent increases in delays and cancellations.

The number of passengers screened at Transportation Security Administration checkpoints hit a pandemic-era record on the Friday leading into the July 4 holiday weekend – 2,490,490.

On Monday, July 11, the TSA screened 2,292,793 – about 88% of the number screened at checkpoints on the same weekday before the pandemic in 2019.

Top image: A traveler walks past American Airlines planes gated at Ronald Reagan Washington National Airport on July 11. (Photo by Nathan Howard/Getty Images)