The past few days’ hot and humid spell is likely to continue through the weekend as well, the Met office has said.
The average maximum temperature in the first 13 days of this month has been a sweltering 33.2 degrees Celsius, higher by two degrees than last year’s corresponding figure of 31.2. In 2011, too, the average maximum in the first 13 days was 31.8 degrees.
Records also show that the amount of rain in the first 13 days of September 2013 was less than the corresponding figure last year but more than the 2011 count.
“Lately, there has been no low-pressure formation over the Bay of Bengal that could result in a big cloud cover. Without one, the sun is beating down from the morning and there is increased solar radiation causing the mercury to climb,” said senior official of the India Meteorological Department, Calcutta.
Satellite pictures show a low pressure area has formed near the Bangladesh coast but it would cause only sparse rainfall in some parts of Calcutta over the weekend.
The city will have to wait till Monday for substantial rainfall that could drag down the mercury.
“The mornings have been very sultry over the last few days. We generally use the AC only in the evenings and at night but on Thursday and Friday, we used it during the day, too,” said Namrata Ghosh, 37, a resident of New Alipore.
The discomfort index — a measure of the effect of temperature and relative humidity on the human body — read 61.6 degrees Celsius at 11.30pm on Friday, 6.6 degrees more than the comfortable limit.
At 2.30pm, however, the discomfort index came down to 58.6 degrees following the formation of a cloud cover.
“Since the monsoon is still active, the winds are bringing in a lot of moisture from the Bay of Bengal. So, the water vapour content, especially in the lower levels of the atmosphere, is pretty high, as is evident in the relative humidity readings,” said an official of the weather department.
Explaining the reason for the development of cloud cover in the afternoons in and around Calcutta, the official said the hot sun was making the water vapour brought in by the monsoon wind overnight to evaporate in the morning, leading to cloud formation. But these clouds are not heavy enough to cause rainfall.