The monsoon this year was predicted to result in scanty rainfall because of the El Niño effect. But climate change seems to have taken over now.
El Niño, strengthening in the Pacific, had delayed the onset of the monsoon and restrained rainfall through June, with the country left with a 40% rainfall deficit by the end of the month. But the scene was to change rapidly. By end-June, as the monsoon entered an active phase, Mumbai and large parts of the western coast of India, much of which had also experienced extreme heat, began to be lashed by excessively high rainfall. As a result, the rainfall loss came down to 20% compared to long term benchmark, as calculated on July 6, 2026.
Experts are of the opinion that this proves that climate change is fundamentally altering the nature of the Indian monsoon, overriding other weather phenomena such as El Niño.
Rainfall pattern is the key, not volume
The critical factor is not the volume of the rainfall, but the pattern. Scientists are pointing out that rising temperatures triggered by climate change are heating the atmosphere and the oceans, leading to more humidity, which is causing fewer rainy days but more intense rainfall.
Mumbai’s recent rainfall demonstrates this changing pattern. During the first week of July, the city experienced four spells of triple-digit rainfall. The Colaba observatory, in south Mumbai, recorded 791 mm between July 1-7, which was more than its climatological average of 768.5 mm.
Santa Cruz observatory, towards the north of the city, also received 879 mm, almost around its monthly normal of 919.9 mm. Such intense bouts of rainfall are becoming a recurrent phenomenon along India’s west, with the weather systems being impacted by the warmer Arabian Sea.
Arabian Sea impact
“Monsoon is presently in an active phase, with several weather systems prevailing across the country,” said Mahesh Palawat, vice president, Meteorology and Climate Change, Skymet Weather.
“There was a depression over Odisha and a cyclonic circulation over Maharashtra, keeping the western and eastern arms of monsoon active. Along with this, continuous moisture feed from the Arabian Sea led to continuous regeneration of clouds over Maharashtra in the last three-four days, leading to heavy rainfall,” Palawat added.
“Mumbai saw delayed onset which is partly explainable by El Niño. But the global warming pattern of warm western Asia and shifted Arabian Sea winds have kicked in as expected,” said climate scientist Raghu Murtugudde, Emeritus Professor, University of Maryland, & retired professor, IIT-Mumbai.
“Both the Arabian Sea and the Bay of Bengal are active, and a low-pressure system is also starting from the Bay of Bengal. When this happens and both sides fire up, the core monsoon zone gets heavy rain and that moisture supply alsogoes over Mumbai. Western Ghats force air to climb, so Mumbai gets lots of rain,” said Murtugudde.
Rain surge
Meteorologists suggest that there has been a significant rise in such deluge-like spells during July and August across Maharashtra, Gujarat, South Rajasthan and Southwest Madhya Pradesh.
A recent study says that land heating across West Asia has been responsible for 46% of the intensified rainfall over northwest India and Pakistan during 1979–2022.The long-term data of IMD bears this out. Compared with 1981–2000, average monsoon rainfall during 2001–2024 has increased by nearly 15% in Mumbai and 23% in Pune, near Mumbai, suggesting that western India’s cities are becoming increasingly more vulnerable to intense rainfall.
According to a recent report ‘Indian Coastal Region: Climate Projections 2021 – 2040’ by scientists from Azim Premji University, parts of coastal Maharashtra and Gujarat are predicted to receive almost an additional week of heavy rains from now.
Suburban Mumbai will receive almost an additional week of heavy rainfall in the near future during the southwest monsoon, says the report. Rainfall data indicates a substantial increase in precipitation across both monsoon seasons. The southwest monsoon, which has a massive 1,749 mm baseline, is projected to grow by 18%.
Urban flooding
While climate change helps explain part of the increase in hazards, urban development has failed to keep up with climate science which could help avert disruptions caused by such extreme weather events.
Experts cite that extreme weather events like this are becoming increasingly common, and cities like Mumbai and Pune need to find a way forward to adapt and build resilience against such extreme events.
“It is no longer a matter of warnings anymore as substantial warnings have been issued well in time. It is now a preparedness and response issue. Irrespective of the rainfall, 100% desilting of drains should be done ahead of Monsoon,” said K.J. Ramesh, former director-general, Indian Meteorological Department. “Rampant urbanisation and concretisation have also contributed to this. Trees have been uprooted because there is no breathing space for the roots because of the footpath and concrete areas. Time to time poorly done pruning also leads to their imbalance. There has to be a plan for restoration of the trees,” added Ramesh.
“Mumbai and Pune have witnessed incessant rainfall over the past 48 hours. Orange alert from IMD in Mumbai and red alert for Pune also indicate continued rainfall, which has impacted day-to-day life,” said Vishwas Chitale, Fellow, Council for Energy Environment and Water (CEEW).
“The Thane flood risk management plan developed by Thane Municipal Corporation and CEEW recommends key strategies such as establishing city-level flood early warning systems, relief and recovery, and reconstruction and restoration to build flood resilience. We need to come out with some practical solutions on the ground to be able to manage urban flooding better,” Chitale said.