The Alipore weather office recorded over 75mm of rain between Thursday evening and Friday evening, one of the rainiest 24 hours this season, but the sky is expected to clear up from Saturday.
The weather office said the location of the monsoon trough over south Bengal and a cyclonic circulation in north Bangladesh resulted in the rain in Kolkata and the rest of Bengal.
The monsoon trough is an imaginary line joining all low-pressure points across the breadth of the country.
The rain led to waterlogging along the kerbs of some roads. KMC officials said there were no reports of waterlogging on any arterial road.
The rain, however, inconvenienced commuters. Parents taking their children to schools faced trouble as traffic moved slower than usual on many roads because of showers in the morning.
“The roads leading to La Martiniere for Girls from Park Circus had heavy traffic around noon. It was raining heavily around that time. Many parents got late to reach the school to pick up their children,” said a mother.
The Jodhpur Park drainage pumping station of the Kolkata Municipal Corporation (KMC) recorded 55mm of rain between 6am and 2pm on Friday. During the same period, 47mm of rain was recorded in Kalighat, 46mm in Kamdahari in Garia, 40mm in Ballygunge and 38mm in Mominpore.
“Under the influence of the monsoon trough and the cyclonic circulation, there is significant moisture incursion. The impact is more in the districts of north Bengal. South Bengal is getting consistent rain, too,” said G.K. Das, director, IMD, Kolkata.
The circulation is tipped to weaken and the weather is likely to improve, he said.
In south Bengal, the sky is expected to start clearing over the next 48 hours. From Sunday, the Celsius will also start rising.