At the Annunciation, when the angel Gabriel appeared to the Virgin Mary to inform her that she would conceive of the Holy Ghost, he also informed her that Elizabeth, her cousin, was already six months pregnant (Luke 1:36).
Mary then journeyed to visit Elizabeth.
 Luke's Gospel recounts that the baby "leapt" in Elizabeth's womb at the greeting of Mary (Luke 1:44).

The Nativity of John the Baptist on June 24 comes three months after the celebration on March 25 of the Annunciation, when the angel Gabriel told Mary that her cousin Elizabeth was in her sixth month of pregnancy, and six months before the Christmas celebration of the birth of Jesus.
The purpose of these festivals is not to celebrate the exact dates of these events, but simply to commemorate them in an interlinking way.
The Nativity of John the Baptist anticipates the feast of Christmas.

The Nativity of John the Baptist is one of the oldest festivals of the Christian church, being listed by the Council of Agde in 506 as one of that region's principal festivals, where it was a day of rest and, like Christmas, was celebrated with three Masses: a vigil, at dawn, and at midday.

It is one of the patronal feasts of the Order of Malta.
At the Annunciation, when the angel Gabriel appeared to the Virgin Mary to inform her that she would conceive of the Holy Ghost, he also informed her that Elizabeth, her cousin, was already six months pregnant (Luke 1:36). Mary then journeyed to visit Elizabeth.  Luke's Gospel recounts that the baby "leapt" in Elizabeth's womb at the greeting of Mary (Luke 1:44).
The Nativity of John the Baptist on June 24 comes three months after the celebration on March 25 of the Annunciation, when the angel Gabriel told Mary that her cousin Elizabeth was in her sixth month of pregnancy, and six months before the Christmas celebration of the birth of Jesus. The purpose of these festivals is not to celebrate the exact dates of these events, but simply to commemorate them in an interlinking way. The Nativity of John the Baptist anticipates the feast of Christmas.
The Nativity of John the Baptist is one of the oldest festivals of the Christian church, being listed by the Council of Agde in 506 as one of that region's principal festivals, where it was a day of rest and, like Christmas, was celebrated with three Masses: a vigil, at dawn, and at midday.
It is one of the patronal feasts of the Order of Malta.
Nativity of Saint John the Baptist