St. Patrick's Day is regarded as a secular holiday by many different countries, especially those with large Irish communities.
With regard to the official Church calendar, the celebration of St. Patrick's Day differs throughout the world.
For example, in most of the United States, St. Patrick's Day is an "optional memorial," meaning that it is not required to be celebrated liturgically and does not supersede the Lenten observance.
This means if St. Patrick's Day falls on a Sunday, the liturgy of the Church does not mention the saint, and the Lenten Sunday readings are read.
However, in places where St. Patrick's Day is a solemnity, it can replace the Sunday celebration.
In Ireland, St. Patrick's Day is always celebrated in the liturgy, even if it falls on a Sunday.
These restrictions apply only to the official liturgy of the Church, and do not dictate the local customs or traditions of individuals or families.
You are free to celebrate St. Patrick every year on March 17, but whether you will find him celebrated at Mass liturgy depends on where you are located. Dispensation from the Lenten abstinence when St. Patrick's Day falls on a Friday is also up to the local bishop.
