21 May,2025 08:20 AM IST | Mumbai | Dipti Singh
Unexpected showers in the Shivaji Park area. Pic/Ashish Raje
A series of atmospheric developments suggest that Mumbai and adjoining regions may witness an early onset of the southwest monsoons this year, according to the India Meteorological Department (IMD) and independent weather experts.
The IMD has issued a yellow alert for Mumbai and the Konkan coast, forecasting heavy rain and thunderstorms over the next four days. Several other districts, including Raigad, Nashik, Pune, Satara, and Kolhapur are under an orange alert, signalling the possibility of extremely heavy rainfall in isolated areas. This burst of pre-monsoon showers has made for an uncharacteristically wet May in Mumbai, typically known for heat waves and high humidity. Since early May, the city has recorded multiple rounds of rain, with IMD's Colaba observatory logging 85.2 mm and the Santacruz station registering 47.4 mm of rainfall, making it the wettest May since 2021. "This May has been much cooler and wetter than normal," said Climatologist Rajesh Kapadia from Vagaries of the Weather.
Monsoon chart for this season. Pic/By Special Arrangement
"We had an unusually strong and southward dipping Western Disturbances (WD) in the first week of May. This ensured that the seasonal high-pressure system over the Arabian Sea was disrupted. After this strong and prolonged WD lasting for a few days, a line of wind discontinuity formed over the peninsular India and Western Ghats, which resulted in fairly regular thunderstorms in these regions stretching from Maharashtra into Kerala/Tamil Nadu, across Karnataka, Telangana and Andhra Pradesh," he added.
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Shubhangi Bhute, director of IMD Mumbai, attributed the early rains to a WD that triggered an upper-level trough over the region. "The rains between May 6 and May 8 were system-induced and not technically part of the pre-monsoon activity. The actual pre-monsoon showers usually began after May 13," she explained.
The Southwest Monsoon has already set in over the southern Bay of Bengal, the Andaman Sea, and the Nicobar Islands, and is advancing towards Kerala over the next 4-5 days. "Current weather systems, such as neutral phases of the El Nino Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) are conducive to an early and potentially strong monsoon," Bhute said.
Kapadia echoed this outlook, noting the formation of an upper air cyclonic circulation (UAC) over the Indian peninsula that is expected to move over the Arabian Sea and develop into a surface low-pressure system by May 22, near the Karnataka-Goa coast.
"This low could intensify into a deep depression or even a cyclone, which would significantly influence monsoon progression. The Southwest Monsoon is already established up to Sri Lanka, and wind patterns suggest a Kerala onset around May 24, nearly a week earlier than usual," said Kapadia.
If current patterns persist, the monsoon could reach Goa by May 27-28 and Mumbai as early as June 1, several days ahead of the normal June 11 onset. "Interior parts of south Maharashtra could also see monsoon rains by the first week of June, followed by north central Maharashtra around June 3," Kapadia stated.
Rushikesh Agre, an independent weather enthusiast known as â@Mumbai Rains' on X, predicted a vigorous start to the season for the West Coast. "The monsoon may reach Mumbai around June 5-6, bringing one of the wettest opening spells in recent memory. A surplus season is on the cards," he said.
Meanwhile, Bhute provided a detailed update on the monsoon's current position. "The Northern Limit of Monsoon (NLM) currently passes through key coordinates from the Arabian Sea to the Bay of Bengal. Conditions are becoming increasingly favourable for its advance over Kerala, Tamil Nadu, Lakshadweep, and northeastern states in the next 4-5 days," she said.
Another official from IMD's Regional Meteorological Centre, Mumbai, said, "As weather systems continue to build, residents across Maharashtra are advised to stay alert and monitor updates from official sources like IMD. With the potential for intense rainfall and evolving cyclonic activity, early preparedness may prove vital this year."