The festival celebrates the spring season and is celebrated in Kerala. It falls after the south-western monsoon has moved away from the state the advent of spring is announced by all kinds of flowers that bloom. Although it is a Hindu festival, it is celebrated by Keralites of all religious communities. The celebrations last 10 days, although the tenth day - called Thiruvonam - is the most festive day of all. New clothes, good food, and clean decorated houses with floral designs mark the day. People watch boat races and folk dances including Pulikkali in which men paint themselves to resemble tigers and leopards.
According to legend Kerala was once ruled by an Asura (a demon or a non-god) called Mahabali, or Maveli. The king ruled in such an exemplary manner that the devas (gods) grew jealous and pleaded with Vishnu (one of the Hindu trinity, the three most powerful gods) to get rid of him. Vishnu took the form of a vamana (dwarf) brahmin and called on Mahabali immediately after his morning prayers when it was the noble king's custom to grant boons to brahmins. Vamana told Mahabali that he wanted land to pray on. Mahabali told him that he could have as much land as he wished. The dwarf said he wanted just three measures of land, each measure being the area that his foot would cover. Mahabali readily conceded the demand. Then Vamana grew to such a size that with just two measures of his feet, he exhausted all the worlds and asked Mahabali how he proposed to give him the promised third measure. Mahabali realise that he had been tricked, but as he was a generous king, he kept his word and showed him his own head, the only place left for him to give away. Vamana put his foot on Mahabali's head and pushed him down into the Patala (netherworld). Vishnu was pleased with Mahabali and granted him a boon. Mahabali was granted that he be allowed to return once a year to visit his beloved subjects. Onam is celebrated as the occasion when the righteous king makes his temporary return from wrongful exile.

Where: Kerala.