It is their traditional New Year when they can enjoy their holidays to the full with no economic hindrance.
Songkran is a fixable feast on the solar calender. It begins on the 13th April and ends on the 15th April, but occasionally in certain years on the 16th April. The Songkran is in fact the celebration of the vernal equinox similar to those of the Indian Holi Festival, the Chinese Ching Ming, and the Christian Festival of Easter