The fairies have three great festivals every year, during Walpurgis Night (April 30), Midsummer’s Night (June 24), and Samhain (October 31).
On Walpurgis Night / Beltaine (also known as May Eve and Walpurgisnacht), the fairies engage in great feasting and occasional fighting.
On Midsummer’s Night (also known as Midsummer Eve) the fairies are at their gayest, dancing merrily around and occasionally stealing beautiful maidens. In at least one Welsh tale, the tale of Einion Las, the fairies would sometimes allow mortals to join in their revel for that one night, and they need not fear the normal dangers associated with dealing with the fae until the next sunrise.
On Samhain (known as All Souls Night and Halloween and All Hallow’s Eve), the fairies are in the darkest of moods. It is this time when the barriers between the material and spiritual worlds are lowest, and the fairies dance with the ghosts of mortals. Only the bravest of men ever go outside alone on this night.
May first and November first are moving days, when the fairies move to their summer and winter homes, respectively.
Robert Hunt gave this brief anecdote:
Richard once witnessed a fairy revel in the Towen–upon which tables were spread, with the utmost profusion of gold and silver ornaments, and fruits and flowers. Richard, however, according to the statement of “Aunt Alcey” (the name by which his wife was familiarly called), very foolishly interrupted the feast by some exclamation of surprise; whereas, had he but touched the end of a table with his finger, it would have been impossible for the fairy host to have removed an article, as that which has been touched by mortal fingers becomes accursed. As it was, the lovely vision faded before the eyes of the astonished labourer.