Ryanair has confirmed that its website and mobile app will close for eight hours for a systems upgrade.
The facilities will go offline from 18:30 on Wednesday, March 22nd.
It is expected normal service will be restored at 02:30 the following day.
The online check-in service will not be available during this period.
Ryanair urged all customers travelling on Wednesday and Thursday to check-in online for their flight today, before the web closure takes place.
New bookings or changes to existing flights will not be possible during this web closure.
Ryanair spokesman Robin Kiely said: “We sincerely apologise for any inconvenience caused by this upgrade, which will further improve Europe’s largest travel website.”