"Calan Mai ([\u02C8kha\u02D0lan \u02C8ma\u02D0j] \"Calend (first day) of May\") or Calan Haf ([\u02C8kha\u02D0lan \u02C8ha\u02D0v] \"Calend of Summer\") is a May Day holiday of Wales held on 1 May. Celebrations start on the evening before, known as May Eve, with bonfires; as with Calan Gaeaf or November 1, the night before (Welsh: Nos Galan Haf) is considered an Ysbrydnos or \"spirit night\" when spirits are out and about divination is possible."@en .