Onam in 2025 begins on August 26 and ends on September 5, with the most important day, Thiruvonam, falling on September 5. The festival is a ten-day harvest celebration primarily observed in Kerala, India, marking the homecoming of the legendary King Mahabali. It includes various cultural activities, feasts, and rituals over this period. The first day is called Atham (August 26), and the celebrations culminate on Thiruvonam, which is seen as the day King Mahabali visits his people.