Spurred by cyclone Remal, the southwest monsoon set in over the Kerala coast and parts of the northeast on Thursday, a day ahead of the date forecast by the weather office.

Weather scientists said that the cyclone, which ripped through West Bengal and Bangladesh on Sunday, had pulled the monsoonal flow to the Bay of Bengal, which could be one of the reasons for early onset over the northeast.

"Southwest monsoon has set in over Kerala and advanced into most parts of northeast India today, the 30th May, 2024," the India Meteorological Department said.

On May 15, the weather office had announced the onset of monsoon over Kerala by May 31.

Kerala has been receiving heavy rains for the past few days resulting in a surplus May rainfall, the weather office data showed.

The normal monsoon onset date for Kerala is June 1 and for Arunachal Pradesh, Tripura, Nagaland, Meghalaya, Mizoram, Manipur and Assam is June 5.

The IMD declares onset of monsoon over Kerala if anytime after May 10 over 14 stations there and neighbouring areas receive 2.5 mm or more rainfall for two consecutive days, the Outgoing Longwave Radiation (OLR) is low, and the direction of the winds is southwesterly.

El Nino conditions are prevailing at present, and La Nina may set in by August-September, scientists said.

El Nino - the periodic warming of surface waters in the central Pacific Ocean - is associated with weaker monsoon winds and drier conditions in India. La Nina - the antithesis of El Nino- leads to plentiful rainfall during the monsoon season.

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