Here is your short paragraph on Onam festival:
This is the harvest festival of Kerala falling in the month of September. Onam has earned an all India character, this is one of the most prominent festivals observed in Kerala.
It coincides with harvest season and is an occasion of spontaneous revelry. The festival celebrates home coming of Maha ‘Bali’, legendary king, who rules over Kerala in an age of plenty but was pushed down to infernal regions by Vishnu in the form of Vamana.
It is now observed as a national festival under government auspices. The most interesting features of Onam are the snake boat races held at several places in palm fringed lagoons. Various kind of boats, beak shaped, take part in these contests.