Night before May 1.
The name comes from the 8th-century St. Walburga (or Walpurgis), an English missionary who ran an important early convent in Germany, May 1 being one of her feast days. In Sweden it is celebrated with bonfires as the beginning of spring. In Germany, as Walpurgisnacht, it was the night witches were supposed to meet in the Harz Mountains (see Brocken ), though the association of witches with St. Walburga is only coincidental. See also Beltane .