Pune: The southwest monsoon has arrived in parts of Andaman Sea and Bay of Bengal, nine days earlier than normal, the India Meteorological Department (IMD) announced on Tuesday."The southwest monsoon has advanced into some parts of south Bay of Bengal, south Andaman Sea, Nicobar Islands and some parts of north Andaman Sea," the weather office said in a statement.

The southwest monsoon normally reaches the Andamans on May 22. Early arrival of the monsoon is rare. The last time monsoons reached the Andamans this early was on May 14, 2017, according to IMD.

The weather office had issued a forecast of early arrival of the monsoon on the mainland on May 27, with a model error of +/- 4 days. Usually, monsoon takes about eight days to progress from the Andaman and Nicobar Islands to Kerala, from May 22 to June 1.

"Conditions are favourable for further advance of SW monsoon over some parts of south Arabian Sea, Maldives & Comorin area; some more parts of South Bay of Bengal, entire Andaman & Nicobar Islands, remaining parts of Andaman Sea; and some parts of central Bay of Bengal during next 3-4 days," IMD said.

Timely arrival of monsoon and its progress across the country is crucial for sowing of kharif crops, vital for ensuring India's food security. The IMD has issued a forecast of above-normal rainfall of 105% in 2025 monsoon season."The early onset of the 2025 southwest monsoon is due to the combination of neutral El Nino conditions and favourable atmospheric and oceanic patterns," said OP Sreejith, head, climate monitoring and prediction group, IMD, Pune.