The 13^th day of the 3^rd month is considered to be the luckiest day of the year for all Witches (especially if it should happen to fall on a Friday), as 13 is the number associated with the traditional Witches' coven and 3 is a powerful magickal number.
In Luxemborg, a Pagan fire festival known as Burgsonndeg is celebrated on this day with the lighting of great bonfires to welcome Spring and the rebirth of the Sun.