Mumbai Monsoon: 2500 deaths reported due to excess rains in 10 years

According to an econometric analysis published in the journal Nature on Wednesday, November 12, 2025, excess rainfall and flooding were responsible for around 8 per cent of Mumbai’ deaths, with slum residents bearing over 80 per cent of the burden.

This brings an average of 2,500 deaths in the monsoon season from 2006-2015. It is “comparable” to deaths from all causes of cancer.

Children face the biggest increase in death risk in the wake of extreme rainfall and flooding, while women are at a higher risk compared to men, according to the study.

Days that saw extremely heavy rains (15 cm or more) raised the city’s death rates by 2 per cent.

Researchers from the US' institutes, including Princeton University and Green Globe Consulting in Mumbai, said inadequate infrastructure such as a poor drainage system can worsen the impacts of extreme weather events and pose a threat to people living in urban areas.

The team analysed death records and rainfall data in Mumbai during 2006-2015 to gauge the mortality rate following an excess rainfall -- for instance, days with 150 millimetres of rain -- and flooding.

Further, 150 millimetres of rainfall in a day causes an increase of 2.2 per cent in the general mortality rate -- 2.9 per cent among slum residents -- in Mumbai in the five weeks that follow, the team found.

The result could be attributed to mechanisms including the spread of flood-related diseases, such as dengue, malaria and typhoid, in the wake of the storm.

The estimates are the first of its kind population-level ones revealing disparities in rainfall-related deaths within a city, the authors said.

They added that the findings of deaths related to rainfall are larger than what is documented in official statistics, highlighting that an investment in improved drainage, sanitation and waste management is urgently needed.

The team also estimated that the mortality costs of rainfall in Mumbai are about USD 1.2 billion per year. Death risk due to rainfall was seen to increase sharply during a high tide, which the researchers said presents a channel through which rising sea levels amplify the effects of a high tide and contribute to excess deaths.