Airline passengers have been warned they may face disruption on Monday morning after more than 100 flights were cancelled due to dense fog at two airports.
Foggy conditions in the south east and east of England caused flights to be grounded at Heathrow and London City airports throughout the day, with the Met Office saying fog was likely to persist late into Monday morning.
A Met Office spokesman said: "We have seen quite dense fog in the south east and east of England today and over night we expect that to become more widespread, with visibility reduced to 50 metres.
"Tomorrow fog will take a while to shift in London, the south east and the east of England up to York, and will only become less widespread in the late morning."
Heathrow airport said it was aware 63 inbound and 78 outbound flights had been cancelled during the day by airlines.
A spokeswoman for the airport said: "Passengers are being re-booked or put up in accommodation by airlines, while some domestic passengers are being taken in coaches to their destination.
"Some delays to flights are also occurring so we advise passengers to check with their airlines before travelling."
Flights were also cancelled at London City Airport, although a spokeswoman for the airport said restrictions had now been lifted.
Gatwick airport said it was experiencing low visibility but it had caused no disruption to flights, while Stansted said today had been "business as usual".
The Met Office also said fog could also cause issue for drivers and warned them to slow down and leave greater distances between themselves and other vehicles.
