The mercury touched a nine-month high and relative humidity soared on Tuesday as the extended spell of balmy weather made way for the familiar sun and sweat of March.
Also on the way are Nor’westers — the summer coolers or pre-monsoon rain-bearers. The first one is expected to storm into Calcutta over the weekend, the weather office predicts.
The maximum temperature on Tuesday touched 36.1 degrees Celsius, a notch above normal, and the highest since the 36.6 recorded on June 9, 2013 — which was 283 days or over nine months ago.
The reading will remain around 36 degrees Celsius over the next three-four days and the discomfort level may go up concurrently because of high humidity.
A cyclonic circulation is pushing up the city’s relative humidity by pulling moisture from the Bay of Bengal. It is likely to bring rainfall in some districts over the next couple of days but not in Calcutta, which will have to bear sultry conditions.
“The first half of March was cooler than usual because of unseasonal heavy rain in Jharkhand, Bihar and Chhattisgarh. Conditions have changed over the past two-three days and it will be hot and humid in eastern India, including Calcutta,” said Gokul Chandra Debnath, director, India Meteorological Department, Calcutta.
Tuesday’s discomfort index — a measure of the effect of heat and humidity on the human body — read 60.6 degrees Celsius, six notches above normal throughout the day.
Weather scientists said Wednesday would be sultrier, the factor that affects the discomfort index more than the mercury.
“When relative humidity is high, people feel uneasy because sweat doesn’t evaporate,” one of the scientists said.
After back-to-back holidays for Dol and Holi, people felt the summer heat when they started for their business or office on Tuesday morning. “I had to keep the car AC on all the way to office,” said Siddharth Seth, 34, a techie who drives from Jadavpur to his Salt Lake Sector V office.
By afternoon brollies and handkerchiefs were out besides copious glasses of ice-cooled fruit juice and colas.
The forecast says the weather will follow this pattern at least for the next three-fours days until conditions become ripe for a Nor’wester.
Scientists at IMD, Calcutta, say a Nor’wester could develop by the weekend if the Chhotanagpur Plateau gets adequately heated till Friday. Traditionally, Calcutta receives two such squalls in March after the halfway mark.
The Calcutta-bound Nor’westers mostly originate in the Chhotanagpur Plateau, which covers much of Jharkhand, while some are born in Odisha, Bihar and Chhattisgarh.
“The air over this plateau heats up and rises, attracting moist air from the Bay to fill the void. The moisture condenses and tall, dark rain-bearing clouds are formed. These clouds begin to move eastward, bringing rainfall to places they pass through,” a weather expert said.