The high moisture level behind the sweaty conditions in the city has kept the Celsius under check at a time northern parts of the country are being fried by the scorching sun.
On Sunday, parts of Delhi recorded a maximum temperature of 49 degrees Celsius, eight notches above normal. The Met office in Alipore recorded a maximum temperature of 34.2 degrees, a notch below normal.
The high moisture content is leading to thunderstorms. The storms are, in turn, preventing the overheating of the earth’s surface, said a Met official.
An official said pressure gradients on the Bay of Bengal ensured the dominance of southwesterly winds in Bengal. The moisture-laden winds are travelling up to eastern parts of Jharkhand.
“There is a trough of low pressure from north to south, extending from Bihar to Tamil Nadu. On the western side of the trough are hot and dry winds from northern India. On the eastern side of the trough are moisture-laden southwesterly winds,” said G.K. Das, director, India Meteorological Department, Kolkata.
A combination of heat and moisture is behind the formation of thunderclouds over Jharkhand, which has been happening almost every day.
The clouds have been taking shape in the afternoon and then moving towards Bengal.
A squall line is being formed along parts of Bihar, Jharkhand and north and south Bengal, said Das.
Between April 30 and Sunday, the city and nearby areas have had around five spells of thunderstorms.
“If there is no rain for three to four consecutive days, the surface of the earth will dry up and the Celsius will start climbing. But that has not been happening,” said Das.
On Saturday night, the clouds reached Kolkata at night and triggered a spell of rain.
On Sunday, too, the clouds were on course to reach Kolkata.
“But eventually they got scattered. Murshidabad, above Kolkata, got decent rain. So did Digha, south of Kolkata,” said a Met official.
By afternoon on Monday, thunderclouds had taken shape over Deoghar and Dumka in Jharkhand. By evening, they had reached West Burdwan, Birbhum and its surrounding areas.