May Bank Holiday weekend, The beginning of May is associated with the Celtic festival Lá Bealtaine. This marked the start of the season of blossoming flowers and fruit trees. Traditionally, belfires are lit on the evening before May Day. Belfires are large bonfires burning wood from a range of types of trees. The different types of wood had different spiritual meanings and were thought to play an important role in the fertility of the land and cattle in the coming year.