The south-west monsoon, the lifeline of many farmers of the country, has set in the south Andaman Sea and the south-east Bay of Bengal a good five days in advance.

The Andaman and Nicobar archipelago had been receiving isolated heavy to very heavy rains over the last two days, along with strong westerly winds and a persistent convection over the Andaman Sea, for the last three to four days.

"With these favourable conditions, south-west monsoon has set in over parts of south-east Bay of Bengal, Nicobar islands and Andaman Sea on Monday," the India Meteorological Department said.

It said that conditions were favourable for further advance of south-west monsoon over some more parts of south-east Bay of Bengal and Andaman Sea in the next two days.

Weather forecasters have predicted widespread rains over Andaman and Nicobar islands during the next three to four days and further strengthening of westerly winds in the region.

India's 235 million farmers rely on the timing of the June-September monsoon season to decide which crops to grow.

The long-range summer monsoon forecast has pegged this season's rainfall as almost near-normal of 99 per cent of the average between 1941 and 1990. The weather office has forecast the onset of monsoon over the southern Kerala [Images] coast a week earlier than the normal June 1 date