The mercury dipped below 11 degrees Celsius on Tuesday, the first time after January 25 in 17 years.

The minimum in the city fell 1.7 degrees Celsius since Monday to 10.7, four notches below normal, as winter on its way out prolonged the cold spell the likes of which has not been seen since 1993.

“Over the past few days, there has been a strong, chilly wind late at night. Last night, my knees were shaking as I waited outside the office around 1.15am to take the night drop,” said Sector V techie Arijit Banerjee.

“In 1993, we saw temperatures of 10.4, 10.9 and 10.4 degrees Celsius on January 25, 26 and 28, respectively, but this year, the chilly phase has stretched even longer,” said a senior official at the India Meteorological Department, Calcutta.

The minimum temperature has been below normal since last Wednesday and hovering around 11 degrees Celsius since Friday.

Since 1995, the mercury has never crept below 11 degrees Celsius post January 25.

The Met office said the cold spell was because of lack of western disturbances in northern India, usual at this time of the year, and predicted it would last a few more days.

“There will be a nip in the air for at least a day or two more. On Wednesday, we expect the minimum to remain around 11 degrees Celsius. It might get warmer after that as a high-pressure area is expected to develop over the Bay of Bengal, causing incursion of moisture inland that would, in turn, check the flow of the northerly wind,” said a weather scientist at IMD, Calcutta.

Two western disturbances are also brewing, one over Jammu and Kashmir and the other over Afghanistan, which may affect the weather here by getting in the way of the northerly wind.

“There is, however, no likelihood of the cold disappearing before 72 hours,” said the weatherman.

Vessel launched

The Garden Reach Shipbuilders & Engineers Ltd launched the last in the series of the eight water-jet propelled Inshore Patrol Vessels, built for the Coast Guard, at the Rajabagan dockyard on Tuesday. Conforming to tradition, Jaishree Pande, wife of commander coast guard (North East), inspector-general KC Pande, launched the ship. The proposed name of the ship is Rajdhwaj.