But the onset of the monsoon at the Kerala coast on the western side is likely to be delayed by three days due to prevailing conditions.

'Southwest Monsoon has set in over some parts of south Bay of Bengal and Andaman Sea,' India Meteorological Department (IMD) said.

It said conditions were favourable for further advance of monsoon over some more parts of Bay of Bengal during next 2-3 days.

The scheduled date for the arrival of over the Andaman Sea is around May 20. But this year, under the influence of the tropical cyclone, Mahasen currently located over the central Bay of Bengal, low level cross equatorial monsoon flow appeared over south Andaman Sea and adjoining south Bay of Bengal, which hastened the advancement of the monsoon in the region.

According to IMD forecast, the monsoon is likely to onset at Kerala coast on June 3 subject to a model error of +-4 days

After arriving over Kerala, monsoon moves gradually to cover the entire country by mid-July.

The IMD in its preliminary forecast has predicted a normal monsoon in the four-month season with a cumulative average rainfall of 98% of the long period average (LPA) of 89 cm.

Monsoon is crucial for the kharif crops such as rice, soyabean, cotton and maize because almost 60% of the farm land in the country is rainfed.