Snow in southern England has been affecting flights
There are delays and cancellations to some flights in and out of Northern Ireland this morning because of heavy snow in England.
Passengers are being advised to check with their airline before travelling.
Monday morning's Aer Lingus flights to and from Heathrow at Belfast International Airport were cancelled.
At the City of Derry Airport and George Best Belfast City Airport, flights to and from Stansted were also cancelled.
Heathrow Airport has had to shut one of its two runways and says it will take around two hours to reopen it.
Gatwick and Stansted airports are open, although fewer aircraft are able to take off.
Twenty three flights had to be cancelled and 18 diverted to other airports after Gatwick closed its runway for two hours on Sunday evening.