The Celsius touched 40 degrees at Kolkata’s doorstep on Wednesday and the Met office sounded a “heat wave” alert across south Bengal till the weekend.
With a maximum temperature of 39.9 degrees Celsius on Wednesday, Salt Lake was as hot as Bankura, which saw the Celsius touch 40 degrees.
“Heat-wave condition is very likely to prevail over the districts of south Bengal during 12-16th April,” said a Met bulletin issued on Wednesday afternoon.
A heat wave is declared when the maximum temperature is five degrees above normal.
But the standout trait of the current spell of heat is that it is unusually dry, said Met officials.
On Wednesday, the minimum relative humidity in Kolkata was 16 per cent. The minimum relative humidity is the general marker of the moisture content in the atmosphere.
It means April 12, 2023, was the driest April day in at least five years (see chart).
A minimum relative humidity of less than 25 per cent is usually associated with the dry winter months, said Met officials.
Sanjib Bandyopadhyay, deputy director general of the India Meteorological Department, Kolkata, attributed the scorching temperature to the dominance of dry northwesterly and westerly winds.
“The last time Kolkata saw rain was on April 1. The lack of moisture is the reason behind the dry spell. It is likely to continue till at least April 16. While a combination of heat and humidity causes a lot of discomfort and constant sweating, dry heat leaves a burning sensation,” he said.
A Met official said the northwesterly winds were now dominant till “deep into the Bay of Bengal”.
“Usually, the dry northwesterly winds are over land. But moisture comes from the Bay of Bengal. This time, there is hardly any moisture incursion even from the Bay,” the official said.
The Met office recorded a maximum temperature of 38.6 degrees Celsius, three notches above normal, in Alipore on Wednesday.
But the official bookkeeping meant little. A tour of the city was enough to get a sense of the heat assault.
Around 1pm, the Park Circus seven-point intersection was reasonably deserted. As were Mayo Road and Chowringhee Road.
Around 2.30pm, the only pedestrian visible on the south-bound flank of Jawaharlal Nehru Road, near the American Center, was a woman, her head and face wrapped in her dupatta, waiting for a bus.
One of every two pedestrians carried an umbrella.
According to the Met bulletin, Kolkata was likely to be most impacted by the “heat-wave conditions” on April 13 and 14.
“On April 13, heat wave condition is likely to prevail at a few places over Kolkata, North 24-Parganas, South 24-Parganas, Howrah, Hooghly, Purba Bardhaman and Purba Medinipur districts,” the bulletin said.
“From April 14 to 16, heat wave condition is likely to prevail over the districts of south Bengal and Malda, Uttar Dinajpur and Dakshin Dinajpur districts of north Bengal,” the bulletin said.
