Southwest monsoon has advanced over Southeast Bay of Bengal, Nicobar Islands and South Andaman Sea on Friday, setting the stage for the four-month rainy season crucial for the country's farm economy.

Earlier this week, the weather office said the onset of monsoon over Kerala, marking its entry into the mainland, would be slightly delayed than the usual date of June 1.

"Southwest Monsoon has advanced into some parts of southeast Bay of Bengal, Nicobar Islands and South Andaman Sea today," the India Meteorological Department said.

Conditions are favourable for further advance of southwest monsoon into some more parts of south Bay of Bengal, Andaman Sea and Andaman & Nicobar Islands during next 3-4 days, it said.

On Tuesday, the weather office had said that the onset of monsoon over Kerala is likely to be on June 4 with a model error of four days.

The monsoon arrived in Kerala on May 29 last year, June 3 in 2021, June 1 in 2020, June 8 in 2019 and May 29 in 2018.

Agriculture contributes around 15 per cent to India's 3.5 trillion dollar economy and a good monsoon helps recharge aquifers and reservoirs besides watering the farms.

The emergence of the El Nino weather pattern has raised concerns over monsoon rainfall in 2023.

El Nino, which is the warming of the waters in the Pacific Ocean near South America, is generally associated with the weakening of monsoon winds and dry weather in India. The El Nino conditions this year follow three consecutive La Nina years. La Nina, which is the opposite of El Nino, typically brings good rainfall during the monsoon season.

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