Kolkata: Monsoon reached Kolkata and most parts of south Bengal on a cloudy Friday even as the city recorded a maximum temperature of 34°C. While some parts of the city received drizzles, rain will be scanty in and around the city over the next seven days, said the Met office. This is the earliest monsoon onset in Kolkata since 2021, when it had reached on June 11. In 2025, monsoon had arrived in Kolkata on June 17.Even though they have reached south Bengal, monsoon currents remain weak. A seasonal trough that now runs from northwest Rajasthan to northwest Bay of Bengal may trigger sporadic rain, said weather scientists at Regional Meteorlogical Centre. “Barring some parts of Purulia, monsoon has reached almost entire Bengal. We will now see very light to moderate rain across south Bengal and Kolkata. Wind and thunderstorms will now cease and they will be replaced by drizzles that last long. It will remain cloudy and the mercury will gradually slide. But since there is no strong system, monsoon rain will not be heavy immediately,” said RMC weather scientist Sourish Bandyopadhyay. Monsoon currents are expected to cover the remaining parts of Bengal on Saturday.This year, the IMD has forecast El Nino conditions that could halt rains at the beginning of monsoon. Most regions, including the east and south Bengal, could be impacted, said meteorologists. This will lead to maximum temperatures remaining above normal for most of June across most parts of India, including east India, while below normal average monthly rainfall is expected during the month.El Nino takes effect when the western part of Pacific Ocean remains relatively cooler than the east. It makes wind travel downwards which is not conducive to the formation of clouds. In contrast, the eastern Pacific, which is far away from Bay of Bengal, experiences reverse conditions, making hot winds spiral up and leading to cloud formation.“Since western Pacific is relatively closer to the Bay of Bengal, from where monsoon currents generate, the latter are likely to be weak during monsoon onset. This will not only reduce rain, but also lead to more rainless days, pushing the temperature up, especially in June. So, we may see weak monsoon currents and infrequent rain after monsoon onset. This does not, however, mean that monsoon would be delayed. It has been progressing on schedule and could reach east India on time. But that doesn’t guarantee adequate rain due to the El Nino effect,” said a weather scientist at Regional Meteorological Centre.El Niño disrupts moist wind currents, causing the monsoon to be delayed or weaker. This heavily affects the seasonal rain that agriculture and local reservoirs depend on.It also triggers intense heatwaves. Instead of continuous rain, east India may experience longer dry spells punctuated by short, heavy bursts of precipitation, which increases the risk of both drought and localized flash-flooding. “A powerful El Niño is brewing in the Pacific Ocean, and it is pushing the country toward a starkly below-normal monsoon. Specifically for east India and regions like Kolkata, this condition is expected to make June exceptionally dry, resulting in a below-normal average monthly rainfall,” said a meteorological scientist.
