Onam 2026 begins with Atham on August 16 and reaches its biggest celebration on Thiruvonam, August 26, with Sadhya, Pookalam, Pulikali and boat races across Kerala. Onam Festival 2026 Dates And Main Celebrations Onam, Kerala’s biggest harvest and cultural festival, will be celebrated with traditional rituals, elaborate feasts and colourful public events in August 2026. The festivities begin with Atham on Sunday, August 16, and continue for 10 day