On one of the busiest travel days of the year, a combination of dismal weather Wednesday and the crush of holiday travelers created gridlock at airports along the East Coast, and by the evening LaGuardia Airport was hit with the highest percentage of flight delays in the country.

A combination of low visibility, dense fog and wind wreaked havoc on air travel throughout the day, and the weather, combined with the numbers of traveling masses, created serious congestion at already delay-prone New York City airports.

“Any little variable that gets thrown in there, LaGuardia is going to be one of the first airports that starts seeing delays, and that’s exactly what happened . . .” said Phil Derner, an aviation consultant and founder of NYCaviation.com.

DataAirport departures, capacitysee alsoNYC-area airport updates

More fog and low visibility are expected Thursday, but Derner said the effect might not be as severe.

The day “is going to be kind of foggy in the morning with low clouds, but I’m not expecting it to be, on the weather side, as bad as it was” Wednesday, Derner said. “A little bit of weather with that increased volume could still be a recipe for some measurable delays.”

Flights arriving at LaGuardia were delayed an average of 3 hours and 17 minutes, the Federal Aviation Administration said on its website.

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And planes departing for LaGuardia were held until at or after 8:15 p.m., the agency said.

Passengers flying into Kennedy Airport faced average delays of 2 hours and 38 minutes.

But those traveling to Newark International Airports encountered even longer delays: an average of 3 hours and 28 minutes, the FAA said.

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Delays in the terminals also abounded: The Port Authority sent out alerts advising travelers to allow extra time to check in to their flight and get through security due to long lines.

As throngs of holiday travelers flocked to reunite with loved ones, LaGuardia had the highest percentage of originating flight delays in the country shortly after 8:30 p.m., with 233 late flights and 65 canceled, according to flighaware.com.

That worked out to a cancellation rate of 11 percent, and a delay percentage of 42 percent.

That topped Chicago O’Hare International’s rates of 1 percent and 33 percent.

“Can’t remember the last time my flight out of #JFK/#LGA was on time,” groaned Twitter user @cedxc2005.

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“I’m going to start DJing things to do, games to play, carols to sing, podcasts to listen to while you’re delayed at #LaGuardia airport #nyc,” tweeted user @lgron.

Some saw the delays as an opportunity for Christmas caroling. A few Spirit Airlines employees at LaGuardia were apparently trying to stir up holiday cheer when they began singing “Jingle Bells” over the loud speaker, a moment captured by several travelers.

At Kennedy Airport, delays were not as severe, but still persisted throughout the day. It had 150 delayed flights shortly after 8:30 p.m., an improvement over the 249 flights running late at 5:30 p.m., according to flightaware.com.

Twenty-two percent of its flights were delayed, and 14 or 2 percent were canceled, shortly after 8:30 p.m. according to flightaware.com.

A Port Authority spokeswoman advised passengers to check their flight status with the airline before heading to the airport.

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Derner asked travelers to remember that delays happen out of regard for safety.

“I think it’s important that people remember that, as frustrating as all these delays are, they’re happening because of the weather in the interest of safety,” he said.

With Joan Gralla