The rainiest month in Kolkata ended with a near 30 per cent deficit this year. The average rainfall for July is around 390mm in Kolkata, according to Met records complied over the past three decades.
This year, the city got around 275mm of rain in July, making the last month the second-driest July in a decade. July 2019 was drier with only around 160mm of rain.
The Met office attributed the rain deficit to the absence of weather systems over the Bay of Bengal.
“A low-pressure area or cyclonic circulation over the Bay of Bengal, preferably on the north Bay which is closer to the Bengal and Bangladesh coastlines, acts like a catalyst for rain in Kolkata and other coastal areas. But there has been none in that area in July,” said G.K. Das, director of the India Meteorological Department in Kolkata.
As a result, the city did not get a single day of heavy rain in July. On a couple of days, there have been sharp spells of rain in different parts of the city and nearby areas. But the showers have not been uniform and widespread.
On Wednesday and again on Sunday, the city and some neighbouring areas received skewed rainfall. While there was waterlogging in some areas, others remained bone dry.
“The character of the showers have been like those thunderstorms associated with the pre-monsoon period,” said a Met official.
The forecast is not great for Kolkata. On Sunday night, the trough passed through the foothills of the Himalayas. As a result, the districts of north Bengal are in the middle of another rainy spell.
“Kolkata and the rest of the coastal areas of south Bengal are unlikely to get heavy rain the next few days. The moisture and heating can lead to the formation of thunderclouds that can trigger localised rain,” he said.
The weather in the city is likely to be hot and humid.
“The discomfort index is going to remain on the higher side. The conditions are going to be extremely sweaty,” said the Met official.
In the middle of July, a low-pressure area had formed over the Bay. Initially, it was over south Odisha and later moved slightly up, but still too far from Kolkata to have any formidable impact.
In the absence of a system on the Bay of Bengal, the arrival of the monsoon had also been meek this year. August’s monthly average for Kolkata is around 345mm of rain.