Heavy rain lashed the city since Wednesday night.

Roads went under water, traffic crawled and schools reported thin attendance in the junior classes.

The north got more rain than the south.

Between 8.30pm on Wednesday and 8.30am on Thursday, Salt Lake got 109.2mm of rain, Dum Dum got 95.2mm and Alipore got 65.9mm.

In Met parlance, 60mm of rain in 24 hours is considered heavy.

The sky looked a menacing grey on Thursday afternoon. The conditions were a throwback to September 13 and 14, when a deep depression — making its way through south Bengal towards Jharkhand — triggered formidable rain in south Bengal.

Rain is likely on Friday as well, said a Met official.

The Met office had on Wednesday predicted that the sky would start improving from Friday.

“The wind pattern in south Bengal was expected to change from southerly to southwesterly. The change is happening but at a much slower pace than expected. The convergence of clouds over south Bengal also continued for a longer duration. That is why the showers prevailed on large parts of south Bengal for a longer duration,” said H. R. Biswas, head of the weather section at the Regional Meteorological Centre, Calcutta.

Even after 1pm on Thursday, several stretches of VIP Road — the main road connecting the airport with the rest of the city — had knee-deep water that slowed down airport-bound and Science City-bound traffic.

Cars were struggling to drive through water on stretches of VIP Road, including near the Haldiram’s bus stop, the Haj House and Teghoria.

The base of the flyover from VIP Road that leads to the airport’s terminal building was flooded on both ends.

Parts of Major Arterial Road that offers an alternative route to the airport through New Town were also flooded in Chinar Park. This led to snarls from City Centre II to the flyover that leads to VIP Road from New Town.

Mohammed Arif, an app cab driver whose vehicle got stalled after crossing the stretch and had steam coming out of the bonnet, said he was headed to the airport’s gate number 1 bus stop as he had to pick up a passenger.

“My car was already sputtering after I drove through knee-deep water at the Chinar Park crossing. It started emitting smoke and the check engine light came on before it stopped and refused to start after I got onto the flyover. I called a mechanic and cancelled the ride,” said Arif.

Residents of several housing complexes like Poddar Vihar, Space Circle on VIP Road near Haldiram’s and others said they had a harrowing time crossing the road.

“The Bagjola and Kestopur canals have swollen because of which the rate of rainwater draining out from the roads had slowed down. We have deployed extra pump sets and teams of labourers but even then progress was slow due to continuous rainfall,” said a PWD engineer.

A Met bulletin pointed to two systems — a cyclonic circulation over central Madhya Pradesh and a trough running from the circulation to north Bangladesh, through Chhattisgarh, Jharkhand and Gangetic Bengal.

“The trough is the main contributor to the showers in south Bengal,” said Biswas.

“As the wind pattern changes from southerly to southwesterly, the intensity of the showers will go down in south Bengal. North Bengal will see a rise in the spread and intensity of showers,” he said.