Irish travellers hoping to get connecting flights at Heathrow and other airports in Britain are being warned to expect delays because of severe fog.
British Airways has been forced to cancel all UK domestic services from Heathrow today as a result of the foggy conditions.
The disruption, which has also affected some regional airports in Britain, has led to some delays at Irish airports.
The delays have also caused disruption at the George Best Belfast City Airport.
Forecasters say fog in England is set to continue into tomorrow when Christmas getaway air travel is due to peak.
A total of around 350 flights at Heathrow Airport were cancelled today, including all domestic UK flights by British Airways and some European services.
All the main Irish airports say they are not experiencing any weather-related problems, but some flights from Britain have been delayed.
Aer Lingus and Ryanair say they plan to operate as normal today, but there will be some delays for passengers travelling to and from London.
BA has also cancelled 100 flights from Heathrow tomorrow, mostly domestic but also flights to Brussels and Paris. Some flights from Gatwick are also affected.
All British Airways flights using Heathrow suffered severe delays yesterday and there were also many cancellations by the airline at Gatwick.
The cancellations were due to the severity of the fog which led air traffic controllers to restrict the number of hourly take-offs and landings.
