With colourful 'pookolams' (floral rangolis), various associations of Malayalees in Delhi and NCR have already kickstarted the celebrations, which present a replica of the community life and the rich culture of the southern state.
During the period of the festival, which began on August 29, entrances of homes are decorated with intricate patterns of floral carpets, similar to a 'rangoli.'
"The floral carpets are made to welcome their king who is believed to visit them on these days. Displayed at the center of these patterns are clay figurines of deities - thrikkakkara appan - decorated with designs from rice paste," says Smitha, a Malayalee living here.
This art of making floral patterns has become a popular form of competition during Onam.
"We started the celebrations of Onam last Sunday by conducting Pookalam competition," says P K Mohandas, President of Jansanskriti, a socio-cultural organisation here.
The traditional 'Ona-Sadhya' (feast) compising a lavish lunch spread out on a plantain leaf is a highlight of the festival. It includes vegetarian food with almost twenty side dishes and payasams (puddings). Typical recipies include Aviyal, Thoran, Olan, pickles, papad, sambar, dal, rice, payasam and buttermilk.
The Kerala House and various other Malayalee associations are scheduled to organise feasts at various parts of the city like Gole Market, the Jawarlal Nehru Stadium etc over the next one month or so.
While food is one aspect of the festival, another is to help the needy and spread joy.
"We already had a round of Onam celebration at the NGO, Nirmal Jyoti, in Vasant Kunj in August, where we organised magic and puppet shows and some dance items for the inmates and also provided them with Onakkodi (traditional dress)and other goodies," says Geo Jacob, Vice-President, Vasant Kunj Malayalee Association.
The Ayappa Seva Sangham also has similar plans for Onam.
"We will organize community kitchen for poor and distribute clothes among them on Sunday," says M G Krishnan, secretary of Ayappa Seva Sangham.
People usually dress up in traditional dresses for the festival.
"The main day of the festival falls this Sunday and is called Thiru Onam. Women wear cotton off white sarees and men off-white dhotis both with zari," says Smitha.
Omcheri M M Pillai, who is associated with all Malayalee societies in Delhi says, Onam is basically a festival that goes on for two months here and sometimes extends further.
"It is celebrated every weekend by the Keralites of Delhi. Celebrations include all, from cultural programs to community service," says Pillai.
Members of the Kerala House here, say, that Onam is more of a nostalgia rather than a festival for those living outside Kerala.
Celebrated during the Malayalam month of Chingam, it honours the mythical portly demon-king Mahabali, whose reign was considered as a golden age in the history of the state.
According to folklore the gods resented Mahabali and to teach him a lesson he was banished to the lower world by Vamana, an incarnation of Lord Vishnu. He was allowed to come back to the state during Onam.
"Our celebrations of Onam start with a pookalam. The first thing I do is make pookalam and then wear traditional Kerala saree and go for cultural activities in the evening. We either get together in Delhi or Gurgaon, whichever we decide upon," says Mini Sam who works as a nurse in a Gurgaon hospital.
The festival also sees a number of dances and theatre performances as well.
In the folk art of "Pulikali" or "Kaduvakali" artists dress as leopards or tigers and enact scenes where tigers hunt goats and they in turn are hunted by man.
Women perform traditional dances like "Thumbi Thullal" and "Kaikottikali", a dance performed around the 'pookalam', with songs praising King Mahabali.
Various cultural programmes include these dances to provide a glimpse of the state here.
"We have registrations for a cultural program from members, youth and children. The various activities include 'Kaikottikali', 'Oppana', Bharatnatyam, Mohiniyattom, folk dances, childrens band, skit and various others," says Geo Jacob.
A program at Jawahar Lal Nehru Auditorium has over 200 artists scheduled to perform. "There are twenty six branches of the All India Malayalee association in Delhi. Each branch will present a program and will mainly include dance forms of Kerala," says Pillai.
The festival is also an occasion to showcase tradition of playing games and sports unique to Kerala such as Kutukutu, Talappanthukali, Kayyankali, Attakalam and archery.