The first half of September had a T20 flourish but the second ended more like a tame Test, resulting in an unexpected swelter.
Met office records show Calcutta had received 308.8mm of rain between September 1 and 15, taking the month’s shower surplus at that stage to a mammoth 97.6 per cent.
The momentum was lost in the second half, with the city recording just 132.4mm of rain, bringing down the month’s surplus to 41.14 per cent.
“The heat has increased following the formation of a low-pressure belt that is still developing. It is currently located near the Andhra coast and drawing moisture from the land. The phenomenon is sucking away clouds from the city’s skies and the sun is beating down,” said Gokul Chandra Debnath, director, India Meteorological Department, Calcutta.
Chances are the low-pressure area will move inland in a day or two, after which the moisture flow is likely to change from land-to-sea to sea-to-land. “The wind system is expected to bring rain to south Bengal and Calcutta in the next 48 hours or so,” Debnath said.
Lack of adequate rain in the second half of the month has propelled the mercury to highs the city has seldom experienced during this time of the year. Of the last 10 days in September, the maximum temperature was more than 35 degrees Celsius on six days and 34-plus on the remaining four.
In the same period in the last five years, the mercury had touched the 35-degree mark only once — September 27, 2010. The average maximum temperature from September 21 to 30 is 35 degrees Celsius, highest since 2007.
The second highest — 33.2 degrees Celsius — had been recorded in the corresponding period in 2009.
which is higher by at least a degree than all other years.
Experts said, this monsoon was “unusual” because it was slow off the blocks and weak for the first two-and-a-half months before pulling itself up in the second half of August and first half of September. But then it ended on a low without the flourish of rainfall that is associated with the end of September.
The initial spells of rain were, however, good enough to ensure that September finished with a plus 41.1 per cent rainfall and was able to lift the overall performance of rainfall in the season to a deficit of around 16 per cent but in the “normal range”.
The deficit was 38 per cent in July-end.
“This year, we didn’t have much rainfall initially in the monsoon and when everyone had given up hope, it made a comeback in September with real monsoon-like rain. But the rainy days didn’t last long and now it’s positively hot,” summed up Behala homemaker Aparajita Guha.
That comeback had, of course, come in the form of 171.9mm of rain in three days in the first week of September and another heavy spell in the middle of the month.
Overall, there were 13 rain days (meteorological term for days when it rains more than 2.5mm) which is close to the monthly average of 13.6 days but only four of them came in the second half.
“In July and August, there was also close to the normal number of rain days but there were huge deficits in terms of total rainfall because there was no days of heavy rainfall. In September, there were three days when it rained more than 85mm and that made the difference,” said a weather scientist.