The southwest monsoon is expected to arrive over Kerala on May 26, nearly six days earlier than normal, according to theIndia Meteorological Department (IMD). The usual onset date is June 1.
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An early arrival of monsoon generally brings hope of relief from heat and a good farming season. Nearly half of India’s farmland depends on rainfall instead of irrigation.
Weather agencies and climate scientists, though, are warning that a developingEl Nino pattern in the Pacific Ocean could weaken the overall monsoon later in the season.
What IMD said
The IMD said the monsoon is likely to set in over Kerala on May 26, with a model error margin of plus or minus four days. Last year too, the monsoon reached Kerala early, on May 24.
The weather office said conditions are favourable for the monsoon to advance over parts of the south Bay of Bengal, the Andaman Sea and the Andaman and Nicobar Islands. Its extended-range forecast also shows widespread rainfall along the southern west coast until May 28.
The onset over Kerala is considered the official beginning of the southwest monsoon season over the Indian mainland. From there, the monsoon gradually moves northward across the country.
Early monsoon does not mean good rainfall
Weather experts have said that an early monsoon arrival does not guarantee good rainfall for the rest of the season.
“There is no correlation between the early onset of monsoon and overall quantum of monsoon rain. In fact, there have been years when the monsoon has arrived early but rainfall has been weak. It depends on how many low pressure systems form or how the surge develops because monsoon moves in surges,” an earlier HT report quoted Mahesh Palawat, vice president, climate and meteorology, at Skymet Weather.
The monsoon often advances in bursts or “surges.” Even if it reaches Kerala early, rainfall distribution later in June, July and August depends on ocean temperatures, wind patterns and the formation of low-pressure systems.
What is El Nino?
El Nino is a climate pattern linked to unusually warm sea surface temperatures in the central and eastern Pacific Ocean. It changes global wind and rainfall patterns and often affects weather across Asia, Africa and the Americas.
In India, El Nino is usually associated with harsher summers and weaker monsoons.
The US National Oceanic and Atmospheric Administration (NOAA) and its Climate Prediction Center have saidEl Nino is likely to emerge between May and July this year and may become very strong later in 2026, as per the Washington Post.
NOAA estimates an 82% chance of El Nino developing during this period. Scientists have also warned that there is more than a 50% chance of it becoming a strong or very strong event between September and November.
Why El Nino matters for India
India receives nearly 70 per cent of its annual rainfall during the June-September monsoon season.
A weak monsoon can affect crop production, food prices, reservoir and groundwater levels, rural incomes and power generation.
Several drought years in India have coincided with El Nino events.
The IMD has already forecast below-normal monsoon rainfall for the 2026 season. It expects rainfall at 92 per cent of the Long Period Average (LPA), with an error margin of plus or minus five per cent.
The LPA for the monsoon season, calculated using data from 1971 to 2020, is 87 cm.
The weather department said below-normal rainfall is likely across many parts of the country. Parts of northeast India, northwest India and south peninsular India may still receive normal to above-normal rainfall.
Weather conditions across India
The IMD has also warned of heatwave to severe heatwave conditions across northwest and central India during most days this week.
The IMD has also forecast heavy to very heavy rainfall over several parts of the country, including northeast India, Kerala, Tamil Nadu, Puducherry, Karaikal and south interior Karnataka over the next three to four days. Heatwave to severe heatwave conditions continue across northwest and central India.
The weather agency also said a well-marked low-pressure area persists over the Bay of Bengal, along with a cyclonic circulation extending into the middle atmosphere.
