The southwest monsoon is expected to reach Kerala six days ahead of the usual June 1 schedule, with the India Meteorological Department forecasting its onset on May 26. The weather department reports that conditions are conducive for the monsoon to move into parts of the south Bay of Bengal, the Andaman Sea, and the Andaman and Nicobar Islands within the next 24 hours. Additionally, heavy rainfall is forecast along the southern stretches of the west coast on May 28.
However, even with the early arrival and forecast of heavy rainfall, it remains uncertain whether the country will receive adequate rains, as the onset of El Nino could weaken the season well before it reaches its peak.
El Nino and IMD's ‘below normal’ monsoon forecast
The meteorological department’s initial long-range forecast for this year has already predicted below-normal rainfall for the June to September monsoon season. The IMD has forecast rainfall at 92% of the long-period average, with a possible variation of plus or minus 5%.
Experts note that an early start does not ensure that the season will be mild.In fact in India, El Nino is associated with harsher summers and a weaker monsoon.
There is no link between an early arrival of the monsoon and the total amount of rainfall it brings. In fact, in some years the monsoon has set in ahead of time but the overall rainfall has been deficient. The outcome depends on how many low-pressure systems develop and how the monsoon surges progress, since the monsoon advances in bursts, said Mahesh Palawat, vice president for climate and meteorology at Skymet Weather.
What is an El Nino? How has it affected monsoon in India?
To begin with the name: the term El Niño dates back to 17th-century Peruvian fishermen, who observed unusually warm ocean currents developing off the Pacific coast of South America around December.
Since it reached its peak around Christmas, they called the phenomenon ‘El Niño de Navidad’, which in Spanish means ‘The Christmas Child’. Eventually, the shortened term, meaning ‘little boy’, came to refer to unusually warm ocean currents at any time of year. This year, atmospheric patterns over the Pacific are expected to confirm the onset of an El Nino event.
How it builds, impacts India
During normal conditions in the Pacific ocean, trade winds blow west along the equator, taking warm water from South America towards Asia.
However, during an El Nino climate pattern, trade winds weaken and warm water is pushed back east, toward the west coast of the Americas, according to the US National Oceanic and Atmospheric Administration (NOAA).
This further suppresses the moisture-laden winds that normally blow toward the Indian subcontinent, sometimes contributing to deficient rains.
Researchers at the US National Oceanic and Atmospheric Administration estimate an 82% chance that El Niño will develop between May and July, with the phenomenon likely to continue into next year. Since India gets nearly 70% of its yearly rainfall during the June–September monsoon period, this has sparked concerns about a potentially weaker monsoon.
Multiple years of drought in India have overlapped with El Niño occurrences. For example, during the significant El Niño episode of 2015–16, the country faced drought-like conditions, widespread crop losses, and acute water scarcity. In those years, India received only 86% of its average monsoon rainfall, while Maharashtra’s Marathwada region experienced an almost 40% shortfall in rainfall.
In 2023 as well, during the El Niño phase, India experienced a 36% shortfall in rainfall in the month of August alone.