Nativity of St. John the Baptist - June 24

Today is the feast of the Nativity of St. John the Baptist.

You probably already know that there are only three birthdays celebrated during the liturgical year: Jesus (December 25), Mary (September 8) and John - today.
The feast coincides with the summer solstice, so of course it's a time of celebration of the season as well, as ancient European traditions, many involving fire on the eve of the feast. This article from Dappled Things  is excellent:

Before it was the title of a Nikolai Gogol short story, St. John’s Eve was one of the most festive days of the year, and also one of the strangest. Much like All Hallow’s Eve, or Halloween, St. John’s Eve (June 23) was a night of revelry, bonfires, treat-begging, and terrifying incursions from the spirit world. The cultural weight of St. John’s Eve has faded in the West, aside from the occasional bonfire party.
A few nights ago I participated in a group reading of Shakespeare’s A Midsummer Night’s Dream, a play set on this same night. The mythical Theseus is cast as the newlywed skeptic who disbelieves in fairies, trying to force an unwanted marriage on the poor Hermia. Meanwhile, the fairy-king Oberon is dealing with his own marital difficulties in questionable ways, particularly by making his queen Titania fall in love with a donkey-headed mortal actor. Many romantic hijinks later, and all the lovers have finally settled with the beloveds they desired. It’s not exactly a St. John’s Eve festival, but the feast’s customary ties to nuptial ceremonies are evident throughout.
Why has Halloween found purchase in popular culture, even to the point of absurd excess, while the spooky June holy day has fallen into disuse? Maybe because our increasingly irreligious society can only bear one annual celebration of preternatural invasions. Maybe the autumn weather has something to do with it—there is something romantically melancholy about the chill air and falling leaves. Maybe its questionable ties to a pagan Celtic festival has given Halloween the aspect of forbidden, and therefore desirable, fruit.
St. John’s birth (his beheading has its own feast day) was heralded by one such fantastical invasion, when St. Gabriel frightened the prophet’s poor father dumb. The closing “Night on Bald Mountain” sequence of Disney’s Fantasia is a St. John’s Eve story, and one could truly imagine the Devil retreating in cowardice at the birth of the Forerunner of Christ. Who knows what temptations the adult John had to face in the desert, but surely they could have competed with St. Anthony’s. The bonfires too are a reminder of the Gospel description of John: “He was a burning and a shining light, and you were willing for a time to rejoice in his light.”

And although the Gospel of the day is, of course, the narrative of the announcement of John's birth to his father in the Temple, the feast nonetheless puts us in mind of what John, as an adult,  said of his role in salvation history:
He must increase; I must decrease.
(John 3:30)
In various other places (can't remember where - sorry) I have read the observation which I'll share with you - we celebrate the coming of John, the Forerunner, on days after  the longest days in which time and seasons turn and after which, the light of day begins to fade, ever so gradually.
I must decrease...
The birth of Christ is celebrated in the days when, finally, after weeks of growing darkness, light gains the upper hand again..
He must increase...