A spell of heavy rain surprised many Calcuttans on Thursday.

The Met department had forecast rain from Wednesday night but there was not a drop till early Thursday and almost everyone took it as another failed forecast.

But the scene changed dramatically from 11am. It became monsoon dark. What followed was rain with rumblings of thunder and gusts of wind.

The Met office recorded 47.7mm of rain till 8.30pm and has sent out a forecast of rain in the city over the weekend.

Calcutta is unlikely to receive rain on Friday but there is a forecast for rain and thunderstorm — similar to what the city witnessed on Thursday — on Saturday or Sunday, said H.R. Biswas, head of the weather section at the Regional Meterological Centre, Alipore.

“We had predicted a spell of rain on February 19-20. Similarly, there is another prediction for rain and thunderstorm in the city on February 22-23. There will be a spell of heavy rain on either of the two days,” said Biswas.

Districts like South 24-Parganas, and West and East Midnapore are likely to receive rain on Friday, the weatherman said.

On Thursday, cars navigated the noon traffic with headlights on.

IT professional Amit Maitra had a hard time reaching his parked car on Prince Anwar Shah Road.

“The rain was so unexpected that I wasn’t even prepared with an umbrella, which was in the car. Once I set out I had a difficult time driving especially around Southern Avenue because even at full swing, the wiper failed to give me a clear view. The headlights had to be switched on,” said Maitra, a senior manager at Cognizant.

He travelled from South City to New Town via Bhowanipore.

“The trough from Gangetic West Bengal to Telengana from north Bangladesh to Telengana across Gangetic West Bengal, interior Odisha and south Chattisgarh extends up to 1.5km above mean sea level,” said a bulletin released by the Regional Meterological Centre.

“The influence of the trough, under which there was strong moisture incursion from the Bay of Bengal, caused the thunderstorm with light to moderate rainfall, hailstorm and gusty winds,” a Met official said.

Biswas said rain is not unlikely or unheard of in February.

“A possibility of rain remains towards the end or the third week of February. We have had more rain in February in 2016 and 2019 than we did this year,” he said.

The city had received 68.2mm of rain on February 28, 2019 and 83.5mm of rain on February 25, 2016, Biswas said.

Thursday’s rain led to waterlogging in key pockets of Calcutta.

Stretches of Central Avenue, MG Road, Rashbehari Avenue and Chowringhee Road, among others, were flooded. A bus stop near the Sarat Bose Road-Rashbehari Avenue crossing was submerged in water with commuters waiting on the road or wading through the waterlogged stretch.

To the south of the bus stop, the water had flooded the road, the pavement beside it and even entered the passage of a building that has a bank.

The edge of the road at Deshapriya Park was waterlogged for quite some time. At Gariahat, the edges of stretches of Rashbehari Avenue were waterlogged. Cars kept to the centre of Rawdon Street to avoid the waterlogging on the sides.

A pavement opposite The BSS School in Ballygunge was submerged and Asutosh Chowdhury Avenue was waterlogged.

Residents said waterlogging on Anandapur Road and a stretch of the Ruby-Rashbehari Connector in Kasba slowed down traffic.

“The stretch of the Rashbehari Connector, from GST Bhavan till Ruby, was waterlogged till 1.45pm, which was about 45 minutes after the heavy spell of rain stopped.

Anandapur Road was waterlogged till a little after 3pm,”said a police officer.

The maximum temperature on Thursday was 27.5 degrees Celsius and the minimum temperature was 23.4 degrees.

The Maximum temperature on Friday is likely to be around 29 degrees Celsius and minimum temperature around 19 degrees Celsius,the Met office has said.