British airports continued to cancel flights on Monday after dense fog grounded dozens of flights over the weekend.

The thick fog began lifting Monday, but air traffic remained disrupted, especially at Heathrow airport. More than 1,000 Christmas travellers had to spend the night at Britain’s biggest airport, where 64 flights were grounded.

Similar situations were reported at Gatwick and London City, a total of 20 flights being cancelled at the mentioned airports, British media informed. Delays were also reported at Stansted, Manchester, Cardiff, Glasgow, Birmingham and Luton.

On Sunday, 140 flights were grounded due to the heavy fog and thousands of people were faced with the unpleasant situation of having to cancel their holiday plans.

According to a spokesman for Heathrow Airport, planes are expected to take off by 1400 GMT and “the situation will improve as the day goes on.”

Airports weren’t the only ones affected by the fog, low visibility causing accidents and traffic jams throughout Britain.

With the fog clearing, traveling conditions are expected to improve, but traffic on roads, rails and air continue to be seriously disrupted.