Monday was the coldest day so far this season, with the mercury dipping to 15.5 degrees, three notches below normal.

On Saturday, the minimum temperature was 22 degrees, three notches above normal. The Met office attributed the sharp plunge to free flow of the cold and dry north-westerly winds into the city.

Early risers and morning walkers felt the bite of the winds. Many of them were wrapped in an added layer of protection. A cover of fog made way for a clear sky and sunshine greeted Calcuttans throughout the day but the wind was persistent. Out came the hoodies and shrugs at many places in the city.

“My alarm went off at 5.30am. But I did not feel like leaving the bed, it was so cold,” said Supratik Sarkar, 29, a Southern Avenue resident and a regular runner at Vivekananda Park.

Met officials said the chance of the mercury dipping below 15 degrees was unlikely over the next few days. In fact, the temperature may start rising again from Thursday, they said.

A depression on the Bay of Bengal is tipped to intensify into a cyclone (it will be called Nivar, named by Iran), and hit Tamil Nadu coast on Wednesday. On Monday afternoon, the system was over 600km south-southeast of Chennai, said the Indian Meteorological Department (IMD).

Chennai and other coastal areas in Tamil Nadu are on high alert.

Calcutta is too far from the system to feel its fury, but it will rob the city of its chill for a couple of days, said a Met official.

“The minimum temperature in Calcutta is likely to remain between 15 and 16 degrees for the next two days. But from Thursday, moisture-laden easterly winds will enter the city and lead to some cloud formation. As a result, the temperature is expected to go up,” said G.K. Das, the director, IMD, Calcutta.

Moisture-laden winds stall the free flow of the cold and dry winds from north India and trigger a rise in temperature.

But the rise in temperature will not be long lasting. Once the moisture is gone and the sky is clear, the mercury will slide again, said Das.

The Celsius is in free fall in the upper reaches of India. The temperature plummeted to minus 3 degrees Celsius in Srinagar on Sunday night, making it the coldest night of the season so far. Delhi recorded a minimum temperature of 6.3 degrees on Monday, also the coldest this season.

The cold winds are making their presence felt in Calcutta as well and Calcuttans are making the most of their favourite time of the year even amid the Covid pandemic.

The Alipore zoo was reasonably busy for a Monday amid a raging pandemic. Many people soaked the winter sun on the Maidan.