They are celebrated in both countries on March 4.
Most feast days are celebrated with a Mass in honor of that saint. If you want to know about local customs, you need to be more specific, as in, "How is St. David's feast day celebrated in Wales?"
The feast day of Saint Patrick was first celebrated in the 9th Century. It begin in Ireland and spread throughout Europe.
The feast celebrated on October 7 is the Feast of the Most Holy Rosary.
Religion
Saint Patrick is known for bringing Christianity to Ireland and is celebrated as the patron saint of the country. He is also credited with driving out snakes from Ireland, a symbolic act representing the eradication of pagan beliefs. His feast day, March 17th, is celebrated as St. Patrick's Day.
St. David of Wales was born in the year 542 at Menevia (now Saint David's), Wales.
Saint David's Day is the feast day of Saint David, the patron saint of Wales, and falls on 1 March each year. The date of March 1st was chosen in remembrance of the death of Saint David on that day in 589, and has been celebrated by followers since then. The date was declared a national day of celebration within Wales in the 18th century. In 2006 Saint David's Day was officially celebrated on 28 February by Roman Catholics and on 2 March by the Anglican Church in Wales, because 1 March 2006 was Ash Wednesday, which is a day of penitence on which feast days are not celebrated.
THE Feast of St. Nicholas of Myra.
It is celebrated on August 15.
Saint Sebastian's feast day is celebrated on the 20th January each year.Saint Sebastian's feast day is celebrated on the 20th January each year.
The feast of St. Joseph is celebrated in Italy and everywhere else in the world on March 19.
The feast of St. Brigit of Ireland is February 1.