Today, the official Thai New Year falls in the fifth month of the Thai lunar year. As we will see, at one time in the past it was celebrated in the first lunar month. The reasons for the many factors that determine the timing of Songkran, as well as the reasons for the change from the first lunar month to the fifth lunar month, are partially found in the origins of the Tai peoples in southern China, to their culture of rice farming throughout the ages, and to their adherence to a Buddhist philosophy which incorporates a large degree of astrological belief from ancient Hindu culture. These features as well as the Thai systems of days, dates, months and seasons are the subject of this article, and it is hoped that from these readers will gain a deeper appreciation for the underlying significance of the Thai New Year.