Mumbai has seen a sharp spike in the number of days that it receives rainfall over 100mm in the past 3 years, according to a study conducted by Brihanmumbai Municipal Corporation’s Disaster Management Department. From 13 such days in 2022 to 14 days in 2023, and 21 days during the monsoon season of 2024, the city has recorded an increase of 61 per cent. This number exceeds the annual average of 16 days a year where rainfall is recorded above 100 mm within a day. For comparison, Mumbai receives an annual rainfall of about 2100 mm in the monsoon months, according to official data.

The study has also revealed that the average of high-intensity rainfall has increased for Mumbai during this time. In the last six years, the average high intensity rainfall received increased to 182 mm, from 131 mm, in a short span of four hours. On July 25, 2024, the city received 267 mm of rainfall in just four hours, compared to 132 mm of rainfall on July 27, 2023, and on July 30, 2022. In the past 10 years, high intensity rainfall in four hours occurred 28 times.

Nikhil Desai, from Action for good Governance and Networking in India (AGNI) which is a network of citizens that interacts with the government to improve services for citizens, said, “For Mumbai, the tangible and immediate impact of this on the lives of its citizens is waterlogging. An ordinary person may not understand the impact completely, but policy makers must be able to stitch together the connection between boosting infrastructure in the city with predictable climate trends that can affect citizens on a day to day and long term basis.”