Thiruvathira is celebrated on the asterism Thiruvathira in Dhanu, the fifth month of Malayalese calendar (Kolla Varsham). This corresponds to the month of December-January according to Gregorian calendar.
Thiruvathira is essentially women's festival. Ladies on this day worship Lord Shiva and pray for conjugal harmony and marital bliss. The other very interesting facet of the festival is the enchanting Thiruvathirakkali dance performed by women on this day.
Thiruvathira is being celebrated for ages now but there is no clear theory about the origin of the festival. Festival is said to be celebrated to commemorate the death of Kaamadeva, the God of love according to Hindu mythology. Some people also consider it auspicious to worship Lord Shiva on this day and take his darshan in a local Shiva temple before the sunrise. Some believe that Thiruvathira is the birth day of Lord Shiva. It may be noted that the Ardra Darshan festival of Tamil Nadu corresponds to Thiruvathira festival of Kerala.
The festival of Thiruvathira is extremely popular amongst womenfolk and more specifically amongst the women of Nair community. Festivities of Thiruvathira begin a week before commencing from asterism Aswathi. Notwithstanding the biting cold of the winter season women wake up as early as 4 am and take bath in the river water. While taking bath women sing songs in worship of Lord Kaamadeva on the rhythm produced by splashing of water with the fist. At the end, women stand holding hands in the formation of a circle and sing songs.
Women observe fast on Thiruvathira. Instead of a rice meal they take preparations of chama (Panicum miliaceum) or wheat besides fruits. There is also a tradition to eat betel leaves of this day. Amongst Namboodiris, Ambalavasis (temple-servants) and Nairs there is a tradition of eating as many as 108 betel leaves on the day.
First Thiruvathira after marriage is called Puthen Thiruvathira or Poothiruvathira. It holds greater significance for the women and is celebrated on a grand scale with lot of gaiety and mirth.
In the communities of Namboodiris, ambalavais and Nairs, having close association with Nambodiris there is tradition called 'Pathirappooochoodal', meaning 'wearing of flowers of midnight'. An image of Lord Shiva is placed in the central courtyard of the house at the midnight of Thiruvathira. An offering of flowers, plantains and jaggery is made to this image. The women then perform the very elegant Thiruvathirakkali or Kaikottikali around the image of Lord Shiva wearing the flowers picked from the offering made to the Lord. Womenfolk also amuse themselves by playing on the Oonjal (swing) on this day. On the night of Thiruvathira women again perform Thiruvathirakkali in a circle at the center of which is placed a lighted brass lamp. It is a wonderful sight to watch women dancing on the rhythm of the song they sing and clapping their hands in unison with grace.