Poya

Poya or Poya Day is the name given to a Buddhist public holiday in Sri Lanka which occurs every full moon day. The Full moon is important to Buddhists all around the world, who have adopted the Lunar Calendar for their religious observances. Owing to the moon's fullness of size as well as its effulgence, the full moon day is treated as the most auspicious of the four lunar phases occurring once every lunar month (29.5 days) and thus marked by a holiday.

Every full moon day is known as a Poya in Sinhala; this is when a practicing Buddhist visits the Temple for the rituals of worship. There are 12 or 13 Poyas per year. The term poya is derived from the Pali and Sanskrit form uposatha (from upa + vas: to fast) primarily signifying "fast day". Generally shops and businesses are closed on Poya Days, and the sale of alcohol and meat is forbidden.

Note that the "day" of the full Moon is not the same as the Gregorian (Western) Calendar day. Therefore, in some cases one finds that the official date of a Poya Day public holiday in Sri Lanka is not on the Gregorian date of that Full Moon. For example, looking at the "Department of Government Printing, Sri Lanka" listing of "PUBLIC, BANK, MERCANTILE AND FULL MOON POYA HOLIDAYS – 2010" one sees that in January they list the full Moon on January 30, but the Navam Full Moon Poya Day is on January 29. The same discrepancy occurs in March, May, July, October, and December of 2010. The actual holiday date is based on the phase of the Moon at the Madhyahana time of day (the variant of Madhyahana which only covers 2 ghatikas). This is analogous to the rules that govern the date of Ganesh Chaturthi.

If a month has two Poya Days the name of the second one will be preceded by ”Adhi” (”extra” in Sinhala) as in ”Adhi Vesak”, ”Adhi Poson”, etc.