British Airways says it has had to cancel around 80 flights out of the airport on Monday.
Image source, PA MediaDozens of flights have been cancelled at Heathrow due to freezing fog.
British Airways, the largest carrier at the UK’s busiest airport, has axed around 80 flights.
Airlines were told on Sunday night they would have to reduce the number of flights they are operating by about 15% due to the weather and Air Traffic Control restrictions.
Temperatures at the airport on Monday morning were as low as -6C and visibility was poor.
Online departure boards at Heathrow show cancellations to destinations including Berlin, Amsterdam and Miami.
Services on Sunday evening were also impacted.
A Met Office yellow weather warning for fog is in place until 11:00 GMT on Monday for parts of southern and eastern England.
In a statement, British Airways said it had “apologised to customers whose flights have been affected” and it was “doing everything we can to get them on their way as quickly as possible”.
It advised customers to check its website before travelling to the airport.
A spokesman for Heathrow said poor visibility was forecast for Monday morning at the airport and across the south-east of England.
“While there may be minor changes to [Monday’s] schedule as a result of the weather, we want to reassure passengers that our colleagues are working in close collaboration with our airline and air traffic control partners to get them safely away on their journeys as quickly as possible,” he said.