Met Department says that this year, the southwest monsoon is likely to set over Kerala on May 27, with a model error of 4 days on both sides. The normal onset date for the southwest monsoon is June 1
The India Meteorological Department (IMD) on Tuesday confirmed that the southwest monsoon has advanced into parts of the south Bay of Bengal, south Andaman Sea, Nicobar Islands, and some regions of the north Andaman Sea. The weather department said conditions remain favourable for further advancement over the central Bay of Bengal and the remaining Andaman and Nicobar Islands in the next three to four days.
While the monsoon gains momentum, attention is also turning to a developing system over the Bay of Bengal. On May 13, the IMD reported, “An upper air cyclonic circulation lay over Andaman Sea between 1.5 km and 7.6 km above mean sea level tilting southwestwards with height.”
Reports indicate that this system could evolve into a low-pressure area between May 16 and 22. If conditions persist, it may intensify into a cyclonic storm between May 23 and 28. If named, the cyclone will be called ‘Shakti’, a name proposed by Sri Lanka.
Should Cyclone Shakti form, it could make landfall between May 24 and 26. Forecasters have identified the coastal regions of Odisha and West Bengal in India, along with Khulna and Chattogram in Bangladesh, as vulnerable. The storm could bring heavy rainfall, strong winds, and coastal flooding, especially in low-lying areas.
In addition to the cyclone threat, the IMD has predicted significant rainfall in several parts of the country due to multiple upper air circulations. Light to moderate showers accompanied by thunderstorms and gusty winds are expected in Jammu-Kashmir, Delhi, Punjab, Haryana, East Rajasthan, and Himachal Pradesh through mid-May.
“Isolated heavy rainfall [is likely] over Arunachal Pradesh, Assam & Meghalaya during 12th-16th and over Nagaland, Manipur, Mizoram & Tripura during May 12-15 with isolated very heavy rainfall over Arunachal Pradesh, Assam & Meghalaya on May 13-14 and over Tripura on May 12 & May 13,” the IMD said. Southern and central states, including Karnataka, Tamil Nadu, Kerala, and Chhattisgarh, are also likely to see pre-monsoon showers.
The meteorological department said, “Conditions are favourable for further advance of southwest 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.”
With multiple weather systems evolving, the IMD continues to issue updates and advisories. Local disaster response teams and meteorological departments remain on alert, especially in areas that may be affected by Cyclone Shakti.
Meanwahile, The India Meteorological Department (IMD) said in an update this week that this year, the southwest monsoon is likely to set over Kerala on May 27, with a model error of 4 days on both sides.
The normal onset date for the southwest monsoon is June 1.
Monsoons are a key indicator that helps analysts gauge the economic outlook of the country’s manufacturing and agricultural sectors.
During the past five years, the monsoon has onset early on two occasions–2022 and 2024. In 2022 and 2024, the monsoon onset was May 29 and May 30, as per IMD data.
In 2024, the southwest monsoon rains in India hit a four-year high, experiencing about 108 per cent of the long-period average at 934.8 mm, data made available by the state-run weather bureau showed. The long-period average in India is 868.6 mm.
In its pre-monsoon forecast in 2024, IMD predicted rainfall across the country to be above normal, at 106 per cent of the long-period average.
In 2025, IMD said the southwest monsoon seasonal (June to September) rainfall over the country as a whole during 2025 is most likely to be above normal (greater than 104 per cent of the Long Period Average).
The advance of the southwest monsoon over the Indian mainland is marked by monsoon onset over Kerala. It is an important indicator characterising the transition from the hot and dry season to the rainy season.
As the monsoon progresses northward, relief from scorching summer temperatures is experienced over the areas.
Southwest monsoon normally sets in over Kerala on June 1, with a standard deviation of about 7 days.
IMD has been issuing operational forecasts for the date of monsoon onset over Kerala from 2005 onwards.
IMD’s operational forecasts of the monsoon onset date over Kerala during the past 20 years (2005-2024) were correct except in 2015. Forecast verification for the recent 5 years (2020-2024) is in the table below.
Above-normal monsoon rains helped farmers sow more crops this Kharif season, which bodes well for the overall agriculture sector. Agriculture is the mainstay source of livelihoods for millions of Indians. Traditionally, Indian agriculture, especially the Kharif season, relies heavily on monsoon rainfall.
