Heavy fog forced the cancellation of about 50 flights Sunday at Heathrow, London’s main airport, British media reported. The mist was expected to clear by mid-afternoon.

An airport spokeswoman advised passengers caught up in the disruption to contact their airlines. "The fog has been quite bad today," she said, according to the Telegraph. "We've had to cancel flights to keep up with the schedule."

The disruption at Heathrow comes on the last day of the school half-term holidays for much of the country, Britain’s Press Association reported.

Paul Knightley, a weather forecaster at MeteoGroup, said: "There is fog and low cloud around from Essex to Devon, through parts of the West Midlands, up to Shropshire and Worcestershire and Merseyside.

"The thick fog is expected to return again tonight so Heathrow could be pretty foggy again tomorrow morning."

Travelers had varied reactions, depending on where they were stuck.