Kolkata gets 20% of annual rain in one night: What caused near-cloudburst and what it means for Durga Puja

A relentless spell of rain lashed Kolkata between midnight on Monday and early Tuesday morning, dumping 252 mm, nearly 20% of its annual average of 1,345.5 mm in just seven hours, and leaving large parts waterlogged.

The downpour claimed at least 10 lives and disrupted rail, road, and air connectivity, just days before the grand Durga Puja festival.

A night of deluge

The rain began around midnight on Monday and continued until early Tuesday morning. The worst-affected areas were Garia (332 mm), Jodhpur Park (285 mm), Kalighat (280 mm), Tospia (275 mm), Ballygunge (264 mm), Chetla (262 mm), Mominpur (234 mm), Beleghata (217 mm), Dhapa (212 mm), Ultadanga (207 mm), Thanthania (195 mm), Belgachhia (178 mm), and Maniktala (169 mm).

The scale of the rain was reminiscent of 1978, when Kolkata was hit by a devastating deluge just ahead of Durga Puja. The city recorded 280 mm in a single day back then, leading to massive flooding. A similar pre-puja downpour in 1986 (259.5 mm) was also witnessed by Kolkata.

Was it a cloudburst?

Although the rain was unusually intense, the India Meteorological Department (IMD) clarified that it did not qualify as a cloudburst. For an event to be called a cloudburst, rainfall must exceed 100 mm in a single hour. Kolkata’s maximum hourly rainfall stood at 98 mm, The Indian Express reported.

Experts explained that the downpour was caused by a low-pressure system that formed over the Bay of Bengal on Monday. The system moved towards Gangetic West Bengal, drawing in large amounts of moisture. “Doppler weather radar images showed high moisture content with clouds reaching heights of 5 to 7 km, contributing to the intense downpour,” said the IMD.

Another low-pressure area is expected to form over the northwest and west-central Bay of Bengal on September 25. While forecasts suggest it will move towards Odisha and Andhra Pradesh, its effect could still bring light rain in parts of south Bengal. However, according to the met department, the rain may take a break for now over West Bengal and possibly not dampen the Durga Puja festivities, according to a report by The Times of India.

Impact on Durga Puja preparations

Durga Puja, the state’s biggest festival, is here and organisers are rushing to finish pandal decorations, lighting, and arrangements.

According to a report by The Telegraph, the rains forced many puja committees to make last-minute changes. Elevated platforms, tarpaulin sheets, waterproof decorations, and emergency drainage systems are being put in place to avoid waterlogging during the festival days.

Electrical safety has become a major concern, with organisers holding urgent meetings with electricians to waterproof connections and avoid accidents.

The Kolkata Municipal Corporation (KMC) has also stepped in, deploying teams to clear waterlogged areas and ensure drains remain unclogged.

Transport and daily life hit hard

The heavy rainfall disrupted Kolkata’s lifelines, with railway yards in Howrah and Sealdah flooded, forcing the Eastern Railway to suspend several suburban services, including Sealdah South and Circular lines.

Air travel was equally hit. Around 100 flights were cancelled, and more than 80 were delayed at Netaji Subhas Chandra Bose International Airport, The Telegraph reported. Airlines such as IndiGo and Air India issued advisories, warning passengers of further disruptions.

The state govt announced Durga Puja holidays in Madhyamik board schools from Tuesday while ICSE and CBSE schools were requested to stay shut for at least two days to tide over the situation. The CM also asked universities to allow study/work from home.