Fog is affecting travel in southern England with some flights cancelled due to poor visibility at London airports.
London City airport diverted all inbound flights on Saturday while Heathrow and Gatwick have also reported disruption.
Passengers have been told to expect delays and to contact their airline before travelling to the airport.
There will be further disruption for travellers over Christmas because of industrial action over pay disputes.
The poor visibility in south-east England caused at least a dozen British Airways flights to be cancelled.
“In common with other airlines, we are experiencing some disruption to our flights,” a BA spokesperson said.
BA warned that there would be knock-on delays due to disruption at Heathrow. It said to expect delays and a “small number” of cancellations, as the airport has restricted landing and take-off.
On Friday, BA cabin crew based at Heathrow said they would strike on Christmas Day and Boxing Day in a row over pay and conditions.
Flight delays: Your rights
- If the delay was caused by an “extraordinary circumstance” you will not be entitled to compensation
- You can claim compensation on flights covered by EU law – this includes any flight departing from the EU, or flights arriving at an EU airport and operated by an EU airline
- You can claim only if the delay was severe – more than three hours – and could have been avoided by the airline
- If your flight is delayed for two or more hours you have the legal right to food, drink, access to phone calls and emails, and accommodation if it is overnight
Source: Civil Aviation Authority
London City airport told passengers that “significant fog in London is continuing to cause flight delays” and that it was closing from around midday on Saturday until Sunday.
The Met Office said to expect cloudy weather throughout Saturday evening in London with areas of mist and fog becoming widespread.
Sunday will “start on a grey and murky note with patchy fog persisting”.
The disruption comes days before a planned 48-hour strike at UK airports called by the Unite union over pay and conditions.
More than 1,500 check-in staff, baggage handlers and cargo crew employed by Swissport will walk out on 23 December.
It is unclear exactly how many airports will be affected, but airlines at Edinburgh, Aberdeen, Glasgow, Leeds/Bradford, Liverpool, Newcastle, Heathrow, Stansted and Manchester airports all employ Swissport staff.
Virgin Atlantic pilots have voted to work to rule from 23 December in a row over union recognition.