Flights resume at O’Hare, Midway after dense fog grounds aircraft on Christmas Eve

Flights resumed at Chicago airports on Christmas Eve after they were briefly grounded for dense and freezing fog.

The weather-related “ground stop” at O’Hare and Midway international airports was completely lifted by 9:30 a.m. after the first reports of grounded flights came after 7 a.m., according to the Federal Aviation Administration.

However, the FAA halted arrivals at O’Hare again shortly before 10 a.m., but did not list a reason on its website.

So far, more than 50 flights have been canceled at O’Hare, and more than 70 flights have been canceled at Midway, split evenly between arrivals and departures, according to the Chicago Aviation Department.

Arrivals at O’Hare are delayed by an average of about 40 minutes, while arrivals at Midway are delayed by less than 15 minutes, the aviation department said.

Departures at O’Hare have been held back by an average of 28 minutes, and at Midway are running with delays of under 15 minutes.

The National Weather Service issued a dense fog advisory for the Chicago area until 10 a.m. Cook, DuPage, Kane, McHenry, Winnebago and Boone are the counties most affected.

The foggy conditions are due to moisture that had blown in from the south in recent days mixing with chillier northerly winds overnight, weather service meteorologist Kevin Donofrio said.

“These are just about the worst conditions you can have for flying,” Donofrio said. “When visibility gets down to a quarter-mile, that’s when it gets really dangerous for planes to land.”

The ground stop comes in the midst of one of the year’s busiest travel periods, as an estimated 5 million people pass through O’Hare and Midway for the holidays.