Andaman and Nicobar, off India's eastern coast, are usually the first areas to receive the monsoon rains, typically around May 20.
The early onset of monsoon comes after the chief of the India Meteorological Department (IMD) said on Tuesday that India looks likely to receive higher rainfall than previously forecast because concern over the El Nino weather event has eased.
The monsoon season, which typically runs for about four months, delivers about 70 per cent of India's annual rainfall and is critical for growing crops such as rice, cane, corn, cotton and soybeans.
As such, they can have a big impact on economic growth and food price inflation.