The sky was dark throughout Friday and the city received persistent rain that started in the early hours and went on till evening with the Met office predicting the mercury to drop from Monday.

The Met office in Alipore recorded 29.6mm of rain in the past 24 hours till 8.30pm. The last time the city had got more rain in January was in 2012, when January 9 saw a downpour of 71.2mm, the met office said.

“The quota of rain is mostly over. There could be one or two spells of drizzle on Saturday. But the sky is likely to remain partially cloudy in the first half,” said a Met official.

On Friday, the overcast conditions and cloudy sky ensured that the sun remained out of sight for the entire day, barring a brief appearance in the morning. The result — the maximum temperature fell seven notches to 18 degrees, the lowest in at least seven years, said a met official.

Though the minimum temperature went up a couple of notches to 15.2 degrees, people felt the “bite of cold” because the day temperature was consistently low.

Darkness descends on AJC Bose Road around noon

A cyclonic circulation over Gangetic Bengal was behind the showers, said G.K. Das, director, India Meteorological Department, Calcutta. The system was over Chhattisgarh and Jharkhand 24 hours ago and moving eastwards.

The rain started around 3.45am on Friday and continued in patches till late evening. New Market received 32mm of rain in the past 24 hours, Behala got 31mm and Cossipore 30mm, according to the Calcutta Municipal Corporation.

The wet weather and chill feel prompted many Calcuttans to stay indoors. People who stepped out were cloaked in woollens and carried umbrellas. “The minimum temperature is likely to remain around 14-15 degrees and the maximum temperature is tipped to rise a few notches over the next few days. But once the moisture is cleared, the temperature is likely to dip from Monday,” he added.

The system led to snowfall in North Bengal. Sandakphu, the highest point in Bengal, experienced a fair bit of snowfall on Friday.

In south Bengal, especially districts like Birbhum, East Burdwan and Hooghly, the untimely rain has posed a threat to winter crops like potatoes and onion. Jagannath Chattopadhyay, deputy director of Agriculture in East Burdwan, said: “The rainy weather is a threat to winter crops, mainly potatoes, which get damaged easily. If the rain continues, the damage in crops will increase.”