Passengers wait in a terminal at Dallas-Fort Worth International Airport (DFW) on Aug. 11, a day after unexpected thunderstorms hit the region.
CNN  — 

Heavy rains in the Dallas-Fort Worth area caused hundreds of flights to be canceled or delayed Monday at the two major airports in the region: Dallas-Fort Worth International (DFW) and Dallas Love Field (DAL).

As of 7:45 p.m. ET, there were 290 cancellations and 1,015 delays at Dallas-Fort Worth International, according to the flight tracking service FlightAware.

Some 54% of flights departing from DFW and 45% of flights arriving at DFW were delayed by the storms, which produced copious rainfall and spurred flash-flood rescues in the region.

Some 13% of flights scheduled to depart from DFW and 15% of flights scheduled to arrive there were canceled.

At the smaller Dallas Love Field, there were 77 cancellations and 193 delays. Percentage-wise, Love Field had fewer delays but roughly the same percent of flights canceled.

In total, there were 1,299 flight cancellations and 7,079 delays across the United States as of 7:45 p.m. ET.

So with 367 total cancellations between the two Dallas-Fort Worth airports, they accounted for over a quarter of all cancellations in the country.

Lightning can ground flights

“Staffing issues continue to affect the industry across the US and Canada, as travelers prepare for the upcoming final summer holiday, Labor Day,” Kathleen Bangs, a former airline pilot and current spokesperson for flight tracking site FlightAware, told CNN Travel.

Flight disruptions become “particularly noticeable on days with high thunderstorm system activity due to continuing limited availability of back-up reserve flight crews,” Bangs said.

“When airports are impacted directly by lengthy storms, ground operations – especially refueling – can end up getting halted, especially if lightning is within the airport perimeter,” she added.

DFW sent out a tweet Monday warning travelers the next few days could be rough.

Parts of Dallas got an entire summer’s worth – over 10 inches – of rain between Sunday afternoon and Monday morning, according to the National Weather Service.

Almost two weeks ago, unexpected afternoon thunderstorms also caused hundreds of cancellations at DFW.

Elsewhere in Texas, Austin-Bergstrom International (AUS) and George Bush Intercontinental Houston (IAH) also had delays and cancellations, but not nearly on the scale of the airports in northern Texas.

However, there were notable delays and cancellations at the three main airports in the New York City area late Monday afternoon: Newark Liberty International (EWR), LaGuardia (LGA) and John F. Kennedy International (JFK).

Together, they had logged 566 cancellations as of 7:45 p.m. ET, surpassing the total at DFW and DAL.

Top image: Passengers wait in a terminal at Dallas-Fort Worth International Airport (DFW) on August 11, a day after unexpected thunderstorms hit the region. (Kirby Lee/AP)