The monsoon has officially departed from Bengal on Monday, the Met office confirmed.
The city got its third straight bright and sunny day on Monday, while most of Bengal was bone dry.
As the dry northwesterly winds tighten their grip on south Bengal, the temperature will start dipping gradually. The proverbial “nip in the air” that will be felt after sundown is still a few days away, said a Met official.
“The southwest monsoon has further withdrawn from some parts of Karnataka, some parts of Telangana, most parts of Maharashtra, entire Goa, remaining parts of Madhya Pradesh, most parts of Chhattisgarh, remaining parts of Bihar, entire Jharkhand, West Bengal and Sikkim and some parts of Odisha and northeastern states,” said a Met bulletin.
The line of withdrawal of the southwest monsoon now passes through Sagar Island in South 24-Parganas, it said.
Weather scientists generally treat three to four rain-free days as a prerequisite to announcing the withdrawal of the southwest monsoon. A dip in the moisture content in the air is another marker of the end of the monsoon. The third, and most significant, marker is a reversal in the flow of winds. The arrival of the winds from north India marks the end of the monsoon. The winds from the direction of the Bay gradually stop flowing into the city.
All conditions are currently being fulfilled, said Met officials. The minimum relative humidity was 56 per cent. A week ago, when the city was experiencing incessant rain, the minimum relative humidity was hovering above 70 per cent.
Dry northwesterly winds are entering south Bengal, even in the lower atmosphere, said a Met official in Alipore.
“For now, the minimum temperature in Calcutta will be around 23-24 degrees Celsius. The western districts of south Bengal are likely to witness a minimum temperature of around 20-21 degrees by next week. There is still some time left before the Celsius dips in Calcutta under 20 degrees,” said the official.
Foggy mornings are also likely in some districts.
The withdrawal of the southwest monsoon begins in Rajasthan, where it enters last. The usual date for the withdrawal process to begin is September 17.
The standard date for the withdrawal of the monsoon from Calcutta is October 10. This year marks the third consecutive instance of the retreat taking place on October 13 in south Bengal.
A system was active on the Bay on June 10, but did not have any impact in Bengal.