Aadi Masam is the fourth month in Tamil Calendar and some people consider the month as inauspicious or bad as Dakshinayana Punyakalam, the night time of Gods, begins in the Aadi month. But numerous unique Tamil rituals and festivals are also observed during Aadi month so some people consider it as auspicious.

In some regions newly married couples stay separate during Aadi month. This is because in earlier days it was considered that if a woman conceives (get pregnant) in Aadi month, she will deliver in March or April the hottest months. This would put the life of mother and child in danger. But this custom is not followed by many people today.

Dakshinayana Punyakalam, the night of Devas, begins on the first day of the month Aadi. The sun changes its direction during this period and next six months is the night time of the gods and ends with Uttarayan in January. Due to this reason, no auspicious events are held in the month.

Numerous rituals are held in Aadi month.

Tuesdays in the month Aadi is highly auspicious and is referred as Aadi Chevvai.

Fridays in the month is dedicated to Goddess worship and is known as Aadi Velli.

Aadi 18 Perukku a festival associated River Cauvery is observed on the 18th day of Aadi month.

Varalakshmi Puja, a popular observance by women, is also observed in the Aadi month. The Friday that comes before the Full Moon, or Pournami day, of Aadi month is chosen to perform Varamahalakshmi Puja.