Thousands of people lined the streets to enjoy the spectacle including pregnant Belfast woman Natalie McQuade, whose due date was yesterday.
“I did not think I would be going anywhere, and thought why not come down!” she joked.
The patron saint’s day was also celebrated in Downpatrick — the reputed burial site of Saint Patrick.
And in Londonderry thousands turned out for the Springtime in Wonderland parade, with lively samba and marching bands.
There were parades too in Omagh, Armagh and Coleraine.
At around 1pm the celebrations continued at Custom House Square with a range of traditional and contemporary music acts, including MOBO award winner Chipmunk.
The celebration was brought to a close by 2008 X Factor finalist Ruth Lorenzo.
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