According to the traditional Hindu lunar calendar, the full moon day is known as Poornima, or Purnima. It is to be remembered that Pournami is the full moon day in South India. Most of the Hindu communities, from morning to evening observe a fast on the day. In 2020, Adhik Maas Purnima date is October 1.
It is to be noted that as per the traditional calendar of North India, the Adhik Maas Purnima happens on the last day in the Adhik month. It is to be highly observed that Adhik Month in Karnataka, Maharashtra and Andhra Pradesh is much similar to the Calendar followed by the Marathi people.
In Purnimant and Amavasyant Hindu lunar calendars, it mostly happens once in 2.5 years and the unique feature is this particular month is treated as extra month. This particular extra month is known as Purushottam Maas and dedicated to Lord Krishna. Locally people call it as Adhik Mahina Sud Padavo (Waxing phase of moon) and Vad Padavo (Waning phase of moon).
The Hindu devotees treat this purnima day as an auspicious day in Hinduism. Many important religious festival and rituals takes place on the full moon day in different regions of the country. Most of the people observe fasting on this particular day and dedicate their prayers to Devi and Mother Goddess. They take food only after the evening prayers and seeing the moon in the sky.