Many people think that there are four weeks of Advent. Well, only in some years does the Season of Advent last four full weeks. In most years, Advent is a little shorter, depending on which weekday December 25 (Christmas!) happens to be that year.

The more precise answer to the question posed above is that there are always four Sundays of Advent, but that the liturgical Season of Advent can be between three and four weeks long. The following table gives the precise dates for the current year, and several past and upcoming years. Below the table are further explanatory notes.

Notes:

• Year - The First Sunday of Advent each Nov./Dec. begins the Church's new "Liturgical Year," which extends throughout most of the next calendar year to the following Advent. Thus, December 1, 2019, was the beginning of the 2020 Liturgical Year and November 30, 2020, is the beginning of the 2021 Liturgical Year. See also my overview chart of the Liturgical Calendar from 1969 to 2100.
• A/B/C - The letters indicated after the years refer to the corresponding Cycle of readings from the Lectionary for Mass. Thus, Advent 2019 (and the rest of the 2020 liturgical year) uses readings from Cycle A, while Advent 2020 (and the rest of liturgical year 2021) uses readings from Cycle B, and Advent 2021 (and the rest of liturgical year 2022) uses readings from Cycle C. See the "Related Pages" below.
• Colors - The liturgical color for most of the Season of Advent in the Catholic Church is violet, while Anglicans and some Protestant Churches use blue. Only on the Third Sunday of Advent are rose vestments used in some traditions. The liturgical colors for Christmas Day and the entire Christmas Season are white or gold (not the red and green of the modern commercial world).
• 3rd Sunday - Traditionally called "Gaudete" Sunday (from Latin, meaning "Rejoice!), because the "Entrance Antiphon" of the Mass for this Sunday is a quotation from Paul's letter to the Philippians: "Rejoice in the Lord always; again I say, rejoice! The Lord is near." (Phil 4:4+5b)
• 4th Sunday - The Fourth Sunday of Advent could be as early as Dec. 18, a full week before Christmas (as in 2016 and 2022), or as late as Dec. 24, making it the same day as "Christmas Eve" (as in 2017 and 2023).
• O Antiphons - On the last eight days before Christmas (Dec. 17-24), special readings are used for the weekday Masses, and the traditional "O Antiphons" are used during the Evening Prayer of Liturgy of the Hours and in the Alleluia Verse before the Gospel reading at Mass.
• Other Liturgical Calendars - All of the information on this page applies to the Latin Rite of the Roman Catholic Church. Some of the other liturgical "Rites" within the Roman Catholic Church, as well as some liturgically-oriented Protestant denominations, follow the same calendar. In most Eastern Orthodox Churches, however, the season of Advent begins already in mid-November (40 days before Christmas, which is not Dec. 25, but on January 7, since they still follow the Julian calendar).

Related Pages:

• An Overview of the Advent and Christmas Seasons
• The "O Antiphons" for the Week before Christmas
• Readings for the Weekdays of Advent & Christmas
• Readings for the Sundays of Advent
• The Catholic Lectionary Website