Anyone who is due to travel by plane in the next few days is advised to check their flight as fog is causing airport disruptions.
A number of flights were cancelled in Ireland, the UK and elsewhere in Europe due to thick fog yesterday making take offs and landings unsafe.
This morning, flights from Belfast City Airport to Manchester, London City and Heathrow airports were cancelled.
The fog appears to be especially severe in London, with 10% of departures from Heathrow airport being grounded.
These weather conditions are expected to last for a few days.