Heavy rain lashed the city on Friday afternoon, sending the mercury crashing.
Officials at the regional meteorological centre in Alipore said there is a chance of rain, accompanied by strong winds, on Saturday, too.
The cause of the cloudburst, officials added, was a low-pressure trough line that had developed over south Bengal, extending from north interior Karnataka to Assam, across Chhattisgarh, Jharkhand and south Bengal.
“This apart, there is an upper-air circulation 2.1 km above sea level over Chhattisgarh and adjoining Jharkhand. The shower was caused by the cumulative impact of the twin phenomena. Since the trough line is almost stationary, it is likely to rain on Saturday, too,” an official said.
There were showers on Thursday night in some areas of the city, too, and the summer heat was more bearable, compared to the past few days.
The sky remained partly cloudy since Friday morning. Around 3 pm, dark rainclouds hung low on the sky and the wind picked up. The sky opened up around 3.30 pm, and the hailstorm raged for nearly an hour.
Waterlogging was reported from many low-lying areas, including stretches of Free School Street, Sudder Street, Topsia, Tiljala, College Street, Thanthania and Amherst Street. The civic authorities pressed the Calcutta Municipal Corporation pumps into service.
Mayor-in-council member in charge of drainage Rajiv Deb said: “We had alerted all our pumping stations on Thursday night. Whatever water accumulated on the streets on Friday was pumped out fast.”