(The Hill) — Thousands of flights were delayed on Saturday and Sunday as rainstorms swept across the mid-Atlantic region and forced airlines to adjust travel times over the busy post-Thanksgiving Day weekend.

On Saturday, 4,400 flights were delayed and 67 canceled, according to flight-tracking website FlightAware.

And another 3,722 flights were delayed on Sunday and 78 flights were canceled as of late afternoon.

The largest share of delays were in New York City, with 172 flights delayed and two flights canceled in the city on Sunday.

The National Weather Station in New York City said the region was expecting up to one inch of rainfall on Sunday with “heavy downpours” through the evening.

In Washington, D.C., four flights were canceled and another 115 were delayed. The Washington-Baltimore region was also experiencing rain and messy weather as well.

Republic Airways delayed 26 percent of its flights, or 227 flights on Sunday, according to FlightAware. Most of the airline’s flights were scheduled to take off from airports on the East Coast.

PSA Airlines delayed 23 percent of its flights on Sunday, or 125 flights, a majority of them at Reagan National airport in D.C.

Frontier delayed 110 flights, or 21 percent of its flights scheduled for takeoff across the country.

Airlines have come under intense scrutiny from the Biden administration and lawmakers this year, who have raised concerns about the large number of flight delays and cancellations amid reported staffing shortages.

Secretary of Transportation Pete Buttigieg fined six airlines more than $7 million this month for failing to refund customers affected by delays and cancelations on time.