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Southwest monsoon marks early onset over Andaman & Nicobar Islands, Bay of Bengal, Arabian Sea

The monsoon onset over Kerala is most likely on May 26, marking the commencement of the four-month monsoon season this year.

2 min readBengaluruUpdated: May 17, 2026 04:58 AM IST

This year's monsoon onset over these regions is early by at least six days compared to normal.

The southwest monsoon marked an early arrival this year over some areas of the southwest and southeast Bay of Bengal, Nicobar Islands and southeast Arabian Sea, the India Meteorological Department (IMD) announced Saturday.

“The southwest monsoon has advanced into some parts of the southeast Arabian Sea, southwest and southeast Bay of Bengal, many parts of Andaman Sea, entire Nicobar Islands and some parts of Andaman Islands, including Sri Vijaya Puram, on May 16,” the IMD said.

This year’s monsoon onset in these regions is earlier by at least six days than normal.

However, the onset here was marked even earlier, on May 13, last year. As per the IMD’s monsoon onset schedule, the normal date for the monsoon onset over the south Andaman Sea, and Port Blair in Andaman and Nicobar Islands is May 22.

There has been an increase in the rainfall activity during the past two days over Nicobar Islands, the Andaman Sea and neighbourhood areas. In addition, the strengthening of the westerly winds and the desired outgoing longwave radiation values indicating presence of convective cloud mass serve as a key criteria for declaring the monsoon onset.

The met department also shared that conditions are favourable for further advancement of southwest monsoon into some more parts of southeast Arabian Sea, southwest and southeast Bay of Bengal, remaining parts of Andaman Islands and Andaman Sea, and some parts of eastcentral Bay of Bengal during the next 3-4 days.

The monsoon onset over Kerala is mostly likely on May 26. That will mark the commencement of the four-month monsoon season this year.

Monsoon onset over Bay of Bengal

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Year	Onset date
2026	May 16
2025	May 13
2024	May 19
2023	May 19
2022	May 16
2021	May 21
2020	May 17
2019	May 18
Source : IMD

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