Southwest monsoon delayed, likely to set in over Kerala around June 4: IMD

A new forecast by the India Meteorological Department (IMD) on Tuesday suggests the monsoon will arrive late this year, in contrast to its earlier prediction that it may arrive early.

According to the IMD, the Southwest monsoon normally sets in over Kerala on June 1, with a standard deviation of about seven days. It marks the beginning of the southwest monsoon season (June-September).

In its latest press note, the IMD said, “Southwest monsoon is likely to set in over Kerala around 4th June, 2026.”

The IMD said the conditions are favourable for the advance of southwest monsoon into some more parts of southwest and southeast Arabian Sea, Lakshadweep Islands, some parts of Kerala and Tamil Nadu, some more parts of southwest, westcentral, eastcentral & northeast Bay of Bengal, and remaining parts of southeast Bay of Bengal around June 4.

Earlier, on May 15, the weather department had claimed that the southwest monsoon may "set in over Kerala on 26th May with a model error of ± 4 days.” However, it got delayed and the department, on May 29, stated that the onset could happen in the following week.

Expect below normal rainfall

The IMD said on May 29 that India could witness "below normal rainfall" overall during the monsoon season (June to September) in 2026. Citing data to support the forecast, it said, "...the southwest monsoon seasonal rainfall over the country as a whole is likely to be 90% of the Long Period Average (LPA) with a model error of ±4%."

Its rainfall prediction for June states that average rainfall for country as a whole during June 2026 is most likely to be below normal (<92% of LPA).

LPA refers to the rainfall recorded over a particular region for a given interval, such as a month or a season, averaged over a long period of time, typically 30 to 50 years. If the monsoon season sees less than 90 per cent of LPA rainfall, the IMD classifies it as "deficient".

The statement added that the southwest monsoon seasonal rainfall is most likely to be normal over Northeast India and below normal over Central & South Peninsular India and Northwest India.

El Nino to be blamed?

One reason for the below-normal rainfall could be the emergence of El Niño conditions, which lead to less rain during the monsoon in the country.

In its press note on May 29, the IMD noted that neutral El Nino-Southern Oscillation (ENSO) conditions are transitioning towards El Nino conditions over the equatorial Pacific region.

"The latest climate model forecasts indicate that the El Nino conditions are likely to develop during the southwest monsoon season," it said.

The IMD said El-Nino conditions are likely to be weak in June, and moderate to strong in September.

The US' National Weather Service had said last month that El Niño is likely to emerge soon (82% chance in May-July 2026) and continue through Northern Hemisphere winter 2026-27 (96% chance in December 2026-February 2027). But the release suggests much uncertainty in its peak strength.

However, latest projections suggest this year's El Niño could become a strong event, potentially comparable to some of the most impactful episodes in recent decades, the UK's Met Office said.

While many termed this phenomenon as “super El Niño”, the World Meteorological Organization says it does not use the term “super El Niño”, saying that "it is not part of standardised operational classifications."

Why is it important to understand monsoon's changing behavior?

The IMD says understanding the changing behaviour of the Indian Monsoon is crucial for agriculture, water management, disaster preparedness, and climate adaptation.

The department shared a research paper on south-west monsoon from MAUSAM (Formerly Indian Journal of Meteorology, Hydrology & Geophysics) journal, and said, “This study revisits and redefines the 'normal' onset and withdrawal dates of the monsoon using updated long-term climatological data and modern statistical analysis.”

It notes that even small shifts in monsoon timing can significantly affect crop sowing, water resources, urban planning, and extreme weather preparedness. "Updated monsoon normals help improve forecast reliability and climate resilience," it says.