The city and the rest of Gangetic Bengal have been warned of heavy rain in the next 48 hours.

A cyclonic circulation over Calcutta has been drawing moisture from the Bay of Bengal. Along with it, the monsoon trough has become active again across Gangetic Bengal.

“Under the influence of the two atmospheric systems, there is likely to be heavy rainfall in Calcutta and other parts of Gangetic Bengal in the next 48 hours,” G.C. Debnath, the director of the weather section at Regional Meteorological Centre, Alipore, said on Wednesday.

The monsoon trough, he added, passes through Varanasi, Purulia and Contai, and extends southeast into the east-central Bay of Bengal.

“We are also expecting heavy to very heavy rainfall in north Bengal, Sikkim and the Northeast in the next two days,” said a Met official.

The city and its adjoining areas received little rain over the past few days, as the monsoon current became weak over Gangetic Bengal.

But it moved again into south Bengal over the past 24 hours, causing moderate rainfall in pockets of the city on Tuesday night.

The city woke up to an overcast sky on Wednesday, with frequent spells of light rain that brought relief from the humid heat.