India’s financial capital and largest city, Mumbai, is extremely vulnerable to climate change-induced floods. Every year, extreme rainfall during the monsoon season, which begins in June and ends in September, results in approximately 8% of the coastal megacity’s deaths, according to the findings of a recent study. And 80% of the people who die during frequent flooding events, especially during high tides, live in the city’s sprawling slum areas.
“Children, particularly those under the age of five, face the biggest increase in mortality risk from rainfall, and women face a greater risk than men,” the researchers explained in their study that was published in the journal Nature on November 12, 2025. “The coincidence of rainfall and high tides is known to overwhelm drainage systems and increase flood hazard in Mumbai and cities worldwide, but its health impacts have not yet been studied.”
They found that a single day of 150mm of rainfall results in a 5.3% increase in five-week mortality among children younger than 5 years old, compared to a 1.6% increase among Mumbai residents in the 5 to 64 years age range. The mortality percentage increased to 2.3% among those who were older than 65 years.