In the Catholic Church, Sundays are usually celebrated according to the season of the liturgical year, such as Ordinary Time.
However, on certain occasions the seasonal Sunday celebration is replaced by a feast.
This doesn’t happen often, but it can when the following criteria are met.
- When a solemnity of the Lord, the Blessed Virgin Mary, or a saint falls on a Sunday.
- When a feast of the Lord falls on a Sunday (i.e. the Transfiguration).
- When the feast of a principal patron of the place, that is, the city or state falls on a Sunday.
- When the dedication of a particular church and its anniversary falls on a Sunday.
- When the solemnity of the title, or of the founder, or of the principal patron of a religious order or congregation falls on a Sunday.
To give a few examples, here are a few feasts and solemnities that can be celebrated on a Sunday.
- Presentation of the Lord (February 2)
- Saints Peter and Paul (June 29)
- Transfiguration of the Lord (August 6)
- Assumption of the Blessed Virgin Mary (August 15)
- Exaltation of the Cross (September 14)
- All Saints Day (November 1)
There are others not listed here, but this gives a brief survey of the various feasts in the Church’s year that are on fixed days. When that day is on a Sunday, it can replace the typical seasonal celebration.