Kolkata Hit by Heaviest Rainfall in 37 Years, Causing Deadly Flooding

On September 23, 2025, Kolkata experienced its heaviest rainfall in nearly four decades, recording 251.6 millimeters within 24 hours—the most significant since 1988. The torrential downpour led to severe flooding, submerging streets and causing major disruptions in transportation. At least 12 fatalities were reported, with nine deaths in Kolkata primarily due to electrocution and two others drowning. The floods also disrupted preparations for the Durga Puja festival, damaging festival structures and clay idols across the city. Authorities deployed pumps and launched relief operations, including food distribution and emergency services. The India Meteorological Department attributed the heavy rainfall to a low-pressure system over the Bay of Bengal and warned of continued rainfall in the region.

The India Meteorological Department (IMD) attributed the heavy rainfall to a low-pressure system over the Bay of Bengal, which moved towards coastal Gangetic West Bengal and neighboring regions, creating strong moisture convergence over Kolkata. This event is ranked as the third-highest single-day rainfall in Kolkata’s September history, following 369.6 mm in 1978 and 259.5 mm in 1986.

The heavy rains led to severe waterlogging, submerging streets and stranding vehicles. Road, train, and air traffic were severely disrupted, with several flights and trains canceled or delayed. Power outages affected multiple areas for hours, compounding residents' difficulties. The floods severely hampered preparations for the upcoming Durga Puja festival, the biggest annual festival of Hindus in West Bengal. Many pandals (temporary structures built for the festival) and clay idols of deities suffered damage across the city.

Authorities deployed water pumps to clear streets and railway tracks. Relief measures, including food distribution and emergency services, were initiated. The state government declared schools and other educational institutions closed on Wednesday and Thursday.

India recorded above-average rainfall during the June to September monsoon season for a second consecutive year in 2025, receiving 8% more rainfall than average, boosted by heavy downpours in September. The IMD predicted more rain due to the low-pressure system over the Bay of Bengal.

The event underscores Kolkata's vulnerability to extreme weather events, exacerbated by urbanization that has shrunk natural drainage channels, worsening waterlogging. The timing of the disaster, just days before Durga Puja, raised concerns about preparations and public safety during the festival.

As Kolkata recovers from this unprecedented rainfall, the incident serves as a stark reminder of the challenges posed by extreme weather events and the need for comprehensive urban planning and climate resilience strategies.