The South-West monsoon is likely to make an onset over Kerala around May 30, with a model error of plus or minus four days, an India Met Department (IMD) update said a while ago.

The normal onset date for Kerala, which brings the rains to mainland India, is June 1. Earlier, the rains had entered the Andaman & Nicobar Islands on May 14, more than a week in advance.

Formation of a cyclonic circulation over the Andaman Sea has resulted in the strengthening and deepening of cross-equatorial southwesterlies. This has led to persistent convective activity and rainfall over the region during the last few days.

As of yesterday, its northern limit passed through Hut Bay in Little Andamans, the IMD said.

Conditions are now becoming favourable for its further advance into some parts of South-west Bay of Bengal, South-east Bay of Bengal and remaining parts of Andaman Sea, Andaman & Nicobar Islands and some parts of east central Bay of Bengal during the next two days.

Past data suggest that there is no association of the date of monsoon advance over the Andaman Sea either with the date of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country, the IMD said.