Pope Francis will fly to Knock Shrine in the morning ahead of a mass in the Phoenix Park, which is expected to draw 500,000 people.
It is envisaged that Knock shrine will open to the 45,000 people with tickets at 6am in the morning.
Pope Francis is due to touch down at Ireland West Airport at 9.20am and will arrive in Knock at 9.50am.
He will spend a total of 55 minutes there, during which he will have some time for private prayer, recite the Angelus and tour the grounds in a popemobile.
The Papal mass tomorrow afternoon at 3pm, which is the centre-piece of the World Meeting of Families (WMOF), will draw a crowd of half a million people to the Phoenix Park.
A number of park-and-ride hubs have been set up to facilitate the crowds as many roads are closed in Dublin city centre.
Gardaí are urging the public to use public transport to attend events in Dublin and Knock.
Pope Francis will leave Ireland for Rome at 6.30pm tomorrow evening.
There will be a wet and windy start to the day tomorrow. Heavy rain will clear eastwards early in the morning and there will be some sunny breaks in the afternoon with scattered showers.