India’s southwest monsoon arrived over Kerala on Thursday, marking the official start of the four-month rainy season, according to the India Meteorological Department (IMD). The onset comes a few days later than the weather department’s earlier forecast of May 26, although the monsoon typically reaches Kerala around June 1 each year.
“The southwest monsoon has further advanced into the remaining parts of southwest and southeast Arabian Sea, some parts of westcentral and eastcentral Arabian Sea, entire Lakshadweep islands, Kerala and Mahe, some parts of Karnataka and Tamil Nadu, remaining parts of Comorin area, southeast Bay of Bengal and some more parts of southwest, westcentral, eastcentral and northeast Bay of Bengal today the 4th June, 2026,” the IMD said, according to PTI.
The arrival of the monsoon is closely watched as it plays a crucial role in India’s agriculture sector, water resources and overall economy. The southwest monsoon season runs from June to September and accounts for the majority of the country’s annual rainfall.
What the IMD expects this year
The development comes days after the IMD revised its seasonal rainfall forecast, projecting below-normal rainfall across the country this year. According to the weather department, rainfall during the 2026 monsoon season is expected to be around 90 per cent of the long-period average (LPA).
The LPA refers to the average rainfall recorded in a particular region over a long period, usually 30 to 50 years, for a specific month or season. Based on rainfall data from 1971 to 2020, the country’s seasonal rainfall LPA stands at 87 cm.
El Nino could influence rainfall this season
Under IMD classifications, seasonal rainfall below 90 per cent of the LPA is considered “deficient”. Weather experts have linked the possibility of below-normal rainfall to the emergence of El Nino conditions in the Pacific Ocean, which are often associated with weaker monsoon rains over India, the news agency reported.
At present, neutral El Nino-Southern Oscillation (ENSO) conditions are transitioning towards El Nino conditions over the equatorial Pacific region. The IMD has said El Nino conditions are likely to remain weak in June but could strengthen to moderate or strong levels by September.
The progress of the monsoon and the evolution of El Nino conditions will be closely monitored in the coming months, as both factors are expected to influence rainfall distribution across the country during the season.