St Patrick’s Day for the year 2020 is celebrated/ observed on Tuesday, March 17th.
St. Patrick’s Day also called Feast of St. Patrick, and St. Patty’s day is observed on March 17 and marks the death date of Saint Patrick who is the patron saint of Ireland. In the early 17th century, it was made an official Christian feast day observed by the Church of Ireland, the Catholic Church, the Eastern Orthodox Church, and Lutheran Church. The day celebrates the arrival of Christianity in Ireland as well as the culture of Ireland, and commemorates the death of Saint Patrick.
Read more here: https://www.calendardate.com/st_patricks_day_2020.htm