Monsoon stalls, set for delayed arrival as Kolkata sweats it out
Times of India | 10 June 2025
Kolkata: Speculations of an early onset notwithstanding, monsoon is set to be delayed yet again in Kolkata and south Bengal. With no rain-triggering system forming over the Bay of Bengal and monsoon currents being slow, the rains will not arrive on Tuesday (June 10), the official onset date in this part of the state. There is yet no indication of an onset within the next three days either. Monsoon, however, reached north Bengal a week ahead of the expected date of June 5 and touched Kerala on May 24, eight days before schedule.Monsoon currents over Odisha and parts of the Bay of Bengal, which needed to strengthen and advance for the monsoon to arrive in south Bengal, remained weak, said the Regional Meteorological Centre (RMC), Alipore. Consequently, it has been dry and humid in Kolkata and most south Bengal districts, with the maximum temperature hovering around 35°C. Kolkata on Monday recorded a maximum temperature of 35.4°C, which could remain unchanged till Wednesday .The weather would not change until at least June 11, said RMC weather scientist H R Biswas. "The usual monsoon onset period has begun. While the normal onset date is June 10, the whole of south Bengal is usually covered by monsoon currents by June 15. But it varies from year to year, and a delay of up to seven days is considered normal. But there is yet no indication of an onset, so it can be concluded that the monsoon will not reach within the normal period," added Biswas.Monsoon currents strengthen, weaken and move in a cyclical pattern, which is not uniform. While it reached parts of Odisha on May 28 and north Bengal on May 29, it has not moved towards south Bengal since. The north and south Bengal currents are different, though. "After a spell of good early monsoon rain, the currents have weakened in Odisha. But a revival now seems to be happening, with the currents beginning to strengthen over Andaman and Odisha. These currents need to strengthen further and merge with the Arabian Sea current for the monsoon to reach south Bengal," said Biswas.The southwest monsoon hit Kerala on May 24, marking its earliest arrival over the Indian mainland since 2009, the IMD has said. The monsoon reached north Bengal on May 29, a week ahead of its normal arrival date of June 5. It, however, covered the entire north Bengal two to three days later.Normally, the southwest monsoon sets over Kerala by June 1 and covers the entire country by July 8. It starts retreating from northwest India around Sept 17 and withdraws by Oct 15. Monsoon currents keep strengthening and weakening, often coming to a standstill for days, delaying onset in various regions. The formation of low-pressure systems over the Bay of Bengal often helps create conditions favourable for an onset and strengthens the monsoon currents. "While this is one of the triggers of monsoon onset, currents can move even without a system. Even after onset, currents don't cause uniform rain across regions. It is often marked by long, dry periods, during which the temperature shoots above normal. Odisha is now experiencing a dry phase. Also, the monsoon sets in phases, which could be delayed if the movement of currents slows down," explained Biswas.In 2024, the monsoon hit Kolkata on June 21. In the last 15 years, the monsoon has reached Kolkata by the scheduled date only on four occasions.