Monsoon ‘likely to hit’ over Kerala around June 4: IMD

Although the arrival date does not correlate with the amount of rainfall, this year is a cause for concern. File | Photo credit: Nirmal Harindran

Revising the forecast for the onset of the southwest monsoon over Kerala, where the weather system makes landfall, the India Meteorological Department on Tuesday (June 2, 2026) said the rainy season is now “likely to start” around Thursday, June 4.

On May 15, the IMD predicted an onset over Kerala on May 26 with a model error of plus or minus four days. The arrival on June 4 also exceeds the upper limit of this window, May 30. This is the first time since 2015 — when the May 30 forecast gave way to a June 5 onset — that the department has failed to call the arrival of the Kerala monsoon correctly. The IMD’s launch forecasts, which rely on its own forecasting model, were accurate every year from 2005 to 2025, but for that one outage.

The IMD said conditions on Monday (June 1) “are favorable for further advance of Southwest Monsoon to some other parts of Southwest and Southeast Arabian Sea, Lakshadweep Islands, some parts of Kerala and Tamil Nadu and Bay of Bengal around June 4”. A cyclonic circulation of upper air off the south coast of Kerala is expected to help this terminal pressure. The IMD forecast has singled out heavy to very heavy rainfall over Kerala in the next six to seven days.

The IMD placed the northern boundary of the monsoon – the cloud edge of the system – along a line running from 10°N/60°E across the southern Bay of Bengal to 22°N/97°E as of Monday (June 1), with rain yet to cross over to mainland Kerala.

Mumbai is being drenched by pre-monsoon showers, waterlogging is slowing traffic in some areas

The IMD declares the onset of monsoon over Kerala any day after May 10 when at least 60% of the 14 designated stations across the state and the adjoining coast — among them Thiruvananthapuram, Kochi, Kozhikode and Mangaluru — record 2.5 mm or more rainfall for two consecutive days. Two additional conditions must hold: westerly winds must propagate up to about 600 hPa (roughly 4.5 km) over the southeastern Arabian Sea, and the outgoing longwave radiation must fall below 200 W/m², a proxy for the deep cloud cover and convection that distinguishes a monsoon from mere rain.

IMD officials told The Hindu that the system has stalled near the coast rather than weakening. The slide comes with a below-normal season forecast, at 90% of the long-term average, under a building El Niño.

Published – June 2, 2026 12:39 PM IST