Blame it on the Bay barrier for the warmest morning in three weeks, plus a blink-and-miss drizzle that kept the day cold.
Calcutta recorded a minimum temperature of 16.4 degrees Celsius, two notches above normal, around 5.30am on Sunday because of a weather system that blocked the flow of cold winds from the north and caused light precipitation by drawing moisture from the Bay of Bengal.
The minimum was up 3.2 degrees from the 13.2 recorded on Saturday morning.
Sunday was the warmest dawn in Calcutta since December 20, when the minimum was 17.4 degrees.
Calcuttans, however, did not quite feel the sudden temperature jump because the day stayed cool with the sun hiding behind clouds. The maximum temperature dived almost three notches to reach 23.5 degrees Celsius.
The weather office said the warm spell would make way for cold conditions — this winter’s typical trend — from Monday and the minimum could fall to 12 degrees Celsius by Wednesday. The reason: the system disrupting the North Wind dissipated on Sunday morning.
An official of the India Meteorological Department in Calcutta ruled out rain on Monday or Tuesday. “The moisture in the air has diminished.”
The morning rain helped clear things up for the chilly northerly to blow again through the day. “I had stepped out for my morning jog when it started raining. I had to rush back for my umbrella. The sun didn’t show up and I loved the overcast conditions… feels like peak of winter,” said Ananya Ghosh, 25, a Tollygunge resident.
“There has been excess moisture in the air because of a cyclonic circulation. The system was travelling east from Rajasthan for the past two days. Between Saturday night and Sunday morning, it crossed Bengal and disintegrated over the Bay of Bengal,” said the Met official.
The rising level of water vapour made the relative humidity rise too. As the circulation closed in on the city, the minimum relative humidity went up from 33 per cent on Thursday to 35 per cent on Friday and 45 per cent on Saturday to 56 per cent on Sunday.
The excess moisture brought clouds to Calcutta and these dissipated as small bursts of rain in a few places between 7am and 8.15am.
“Had there been more rain, the city would have got rid of more moisture and the chill would have returned fast. But this did not happen. Given the circumstances, the cold would return gradually,” said a weather scientist.
The minimum temperature will drop by a degree every day between Monday, when the minimum is expected to be 14 degrees Celsius, and Wednesday when it is likely to touch 12.
Some of the suspended moisture will turn into morning fog on Monday and Tuesday. The chilly spell after Wednesday may continue a few days since no weather system is brewing in the vicinity.
JU poll on Jan 28
The Jadavpur University student union election will be held on January 28. Students without identity cards would not be allowed to enter the campus on poll day, officials said.
CCTVs will be installed on the six campuses of Calcutta University to monitor the student union poll on January 18. The university authorities decided to put cameras following advice from Calcutta police, said VC Suranjan Das.