Unlike Lent, which is always 40 days long, the length of Advent can vary widely. This year, Christmas falls on a Sunday so Advent is as long as it can possibly be: 4 full weeks (28 days). Next year, Christmas falls on a Monday and Advent will be as short as it can possibly be. Sunday morning, the 24th of December will be the Fourth Sunday of Advent. Sunday afternoon, Christmas Eve begins the Christmas Season. The Fourth Week of Advent is literally only several hours long. In 2023, Advent will last a total of 21 ½ days. (And yes, we will attend Mass twice next year on Christmas weekend: once for Sunday and once for Christmas. Plan now to spend a lot of time in church!)