Dense fog was affecting flights using London-area airports this morning.
British Airways urged passengers to check the status of their flight before travelling to the airport.
“Fog across parts of southern England on Monday is affecting some flights to and from London’s airports this morning,” the airline said.
“For safety reasons air traffic control is having to allow greater space between landing aircraft and this in turn will result in a reduced number of aircraft being allowed to land each hour.
“We are sorry for the disruption and delays being caused by the poor weather and will do all we can to minimise the effect it has on our operations.”
CityJet, which operates from London City airport, said: “Fog and low visibility is affecting much of the London area this morning. Flight delays expected.”