Flights leaving Dublin airport today have been delayed and many were cancelled due to heavy fog.
An Aer Rianta spokeswoman said passengers should expect delays of up to two hours. Twenty-five inbound and outbound flights have been cancelled and a number have been diverted away from Dublin.
She said passengers should consult their airline for information on delays and check-in times.
Tens of thousands of passengers will be affected by the delays. Some 65,000 to 70,000 pass through Dublin on an average weekend at this time of the year.
The Ryanair website has listed ten flights that have been cancelled but said some additional flights had been laid on between Dublin and Liverpool and Dublin and Aberdeen.