Kolkata woke up on September 23, 2025, to a weather event that has etched itself into the city’s climate history. According to the India Meteorological Department’s (IMD) Alipore Observatory, the city received 247.4 mm of rainfall in 24 hours between 8:30 AM September 22 and 8:30 AM September 23.
This intense downpour was not just another monsoon shower—it became one of the heaviest September rainfalls in nearly four decades. To put it in perspective:
- September 28, 1978: Kolkata recorded 369.6 mm of rain in 24 hours — the city’s highest September rainfall ever.
- September 26, 1986: The second-highest at 269.5 mm.
- September 23, 2025: With 247.4 mm, this event has now taken the third spot in the all-time September rainfall list at Alipore.
What makes this event even more dramatic is the contrast with the rest of the month. From September 1 to 22, Kolkata had received 178.6 mm of rain. In just one night, the city surpassed that entire three-week total.
Rainfall Beyond City Limits
The downpour was not restricted to central Kolkata. Different neighborhoods and suburbs experienced extreme variations, some witnessing even heavier local showers:
- Garia Kamdahari: ~332 mm
- Jodhpur Park: ~285 mm
- Kalighat: ~280.2 mm
- Topsia: ~275 mm
- Ballygunge: ~264 mm
In the southern fringes like Sonarpur, rainfall crossed 247 mm overnight, flooding homes and markets. Pumps were deployed to drain water, but overflowing canals worsened the crisis.
Disrupted City Life and Human Tragedy
The immediate consequences of the rainfall were devastating:
- Casualties: At least seven people lost their lives due to electrocution after coming in contact with waterlogged electrical wires and transformers.
- Transport Chaos:
- Metro and suburban train services were partially suspended.
- Flight operations at Kolkata airport were disrupted, with multiple cancellations and delays.
- Road transport almost came to a standstill as water submerged cars, buses, and motorcycles.
- Waterlogging: Key roads in South Kolkata, Park Circus, Kalighat, Behala, and New Alipore were submerged under knee-to-waist-deep water. Many residential areas reported water seeping into ground-floor homes.
- Power Cuts: To prevent accidents, electricity supply was cut in several waterlogged neighborhoods, leaving thousands of families in darkness through the night.
Even the residence of Mayor Firhad Hakim, who is also the state’s Municipal Affairs Minister, was affected, showing how widespread the flooding was.
Why Did This Rainfall Happen?
Meteorologists clarified that this event was not linked to a cyclone. Instead, it was caused by:
- A low-pressure area over the north-east Bay of Bengal.
- Strong monsoon currents converging over Gangetic West Bengal.
- Convective thunderstorms that intensified during the night, leading to localized cloudbursts.
Experts from IMD noted that while heavy rains are typical in Kolkata during September, the concentration of rainfall in such a short period—most of it overnight—was unusual.
Historical Perspective
This event has revived memories of legendary rainfalls in Kolkata’s past:
- 1978 floods: When nearly 370 mm of rain paralyzed the city and caused days of waterlogging.
- 1986 downpour: Again, over 260 mm of rain disrupted life severely.
- 2007 floods: Kolkata received 174.4 mm in 24 hours, but even that pales compared to the 2025 deluge.
This makes the 2025 event a once-in-a-generation rainfall, underscoring the city’s continuing vulnerability to extreme monsoon patterns.
Impact on Daily Life
- Schools and colleges: Several educational institutions declared holidays due to unsafe conditions.
- Markets and businesses: Many remained closed as traders struggled with waterlogged shops.
- Hospitals: Emergency services were stretched as ambulances faced delays in flooded streets.
- Ordinary citizens: Families in low-lying areas spent the night bailing out water. Residents described the experience as “the worst overnight flooding in years.”
The timing of this disaster has raised additional concern: it struck just days before Durga Puja, Bengal’s biggest festival, raising fears about preparations and public safety.
Forecast for the Next 24 Hours
According to IMD’s latest forecast:
- Weather: Cloudy skies with light to moderate rain expected through September 24.
- Temperature: Maximum around 28°C, minimum around 24°C.
- Flood risks: High tide in the Hooghly River could worsen waterlogging, since drainage canals are already full. Authorities warn that normalcy may take 48 hours in many localities.
Broader Climate Concerns
Meteorologists and climate scientists have flagged Kolkata’s growing vulnerability:
- Urbanization has shrunk natural drainage channels, worsening waterlogging.
- Climate change has made extreme weather events more frequent in South Asia.
- Similar heavy rainfall episodes have been recorded in Mumbai, Chennai, and Bengaluru in recent years, raising questions about urban resilience.
Experts stress that unless drainage and flood-prevention systems are modernized, Kolkata will continue to suffer from crippling floods after extreme rainfall events.
For the first time in nearly four decades, Kolkata experienced a record-breaking September rainfall that disrupted life across the metropolis. With over 247 mm in just 24 hours, the city found itself submerged under water, grappling with tragedy, traffic paralysis, and infrastructure breakdown.
While the skies may clear in the coming days, the event serves as a stark reminder of how vulnerable Kolkata remains to sudden weather extremes. For the city’s residents, September 23, 2025, will be remembered as the night when the rain returned with the force of history.
