Passengers arrive at a Southwest Airlines Co. curbside check-in area at Midway International Airport (MDW) in Chicago, Illinois, U.S., on Monday, Oct. 11, 2021. Southwest Airlines Co. disruptions moved into a fourth day, with 355 canceled flights, or 10% of its daily schedule, on Monday, the latest in a series of setbacks at the carrier. Photographer: Luke Sharrett/Bloomberg via Getty Images
CNN  — 

Dense fog in the Chicago area caused delays and cancellations on Sunday morning at Midway Airport amid the busy travel rush.

The Federal Aviation Administration issued a ground stop at Chicago’s Midway Airport for most of Sunday morning due to low visibility in the area, but it has since been lifted.

There is now a residual FAA ground delay, which is averaging around 2 hours for inbound flights, the FAA reports.

“Dense fog continues across the area this morning, but is expected to gradually improve going into this afternoon,” US National Weather Service Chicago Illinois said in a Facebook post. “Exercise caution if traveling over the next few hours. For those traveling via sleigh, utilizing your reindeers’ nose lights is advised.”

Chicago Midway is the fourth-busiest hub for Southwest Airlines. A spokesperson told CNN they adopted “an all-hands on deck” posture to help customers work through Sunday’s weather issues including accommodating customers on alternative flights.

“We continue to experience some delays and diversions as fog remains a factor,” the airline said, “We apologize for the inconvenience to our Customers as we work to get them to their destination safely.”

Southwest had 200 departures a day scheduled at Midway during the holiday weekend and at least 58 flights were canceled Sunday, the airline said in the statement.

Nationwide, delays and cancellations have remained low for Southwest and the rest of the nation’s airlines this holiday weekend.