MIAMI (NewsNation) — Tens of thousands of flyers had their travel plans upended over the weekend after airlines canceled thousands of U.S. flights as thunderstorms hit the East Coast.

Another 1,790 flights were canceled as of Monday morning, according to tracking service FlightAware. Nearly 15,000 flights were delayed.

The three major airports in the New York City area and Reagan National Airport outside Washington, D.C., recorded the most cancellations.

On Saturday, more than 7,200 flights were delayed, and close to 1,000 flights were canceled with more than 6,300 delayed on Sunday.

Travelers have been hit with widespread cancellations and delays this summer. Travel bounced back faster than expected — to about 88% of pre-pandemic levels in July — and airlines weren’t able to increase staffing fast enough. They have been cutting back on schedules in an attempt to make remaining flights more reliable.

Airlines flying in the U.S. had a bad June, canceling more than 21,000 flights, or 2.7%, up from 1.8% in June 2019, before airlines pushed workers to quit during the pandemic. The airlines did better in July, however, canceling about 14,000 flights, or 1.8%.

Delays have been more persistent — above 23% in both June and July.