The southwest monsoon is expected to reach Kerala on May 26, six days earlier than the usual June 1, though the emerging El Niño phenomenon may undermine the season before it reaches peak intensity, the India Meteorological Department said on Friday.
The IMD said conditions are favorable for the system to advance over parts of the southern Bay of Bengal, Andaman Sea and Andaman and Nicobar Islands within 24 hours. Heavy rains are expected along the southern parts of the West Coast until May 28.
Read also– Monsoon arrival in Kerala on May 26: IMD
In 2025, the monsoon last reached Kerala on May 24. The Meteorological Agency stated that this year’s forecasts carry a margin of error of four days. The natural date of June 1 carries a standard deviation of about 7 days, meaning that early arrival is not unusual – but early arrival has historically provided no protection against a weak season.
What the experts said
“There is no relationship between the early onset of monsoon and the total amount of monsoon rainfall. In fact, there were years when the monsoon arrived early but the rainfall was weak. It depends on how many low pressure systems form or how the surge develops because the monsoon moves in waves,” said Mahesh Palawat, Vice President, Climate and Meteorology at Skymet Weather.
But this year, weather signals from the Pacific are on track to confirm the arrival of El Niño. The US Climate Prediction Center said on Thursday that El Niño “is likely to appear soon” and could reach “very strong” levels later in the year. Scientists at the National Oceanic and Atmospheric Administration estimated the probability of El Niño appearing between May and July at 82%, and the event is likely to continue until next year. There is currently a greater than 50% chance of it becoming strong or very strong between September and November, NOAA charts show. Seasonal models indicated the possibility of an unusually strong event.
Read also – A “super” El Niño phenomenon will hit the Earth in the coming months; The world is preparing for extreme weather conditions
In India, El Nino is associated with harsher summers and weaker monsoons. The first phase of IMD’s long-range forecast forecasts below-normal rainfall for the June-September season: 92% of the long-period average, with a margin of error of plus or minus 5%.
The average LPA, calculated over the period 1971-2020, is 87 cm. Below normal rainfall is likely in large parts of the country, with normal to above normal rainfall expected only in parts of northeastern, northwestern and southern peninsular India. IMD is expected to release its forecast for the second phase by the end of this month.
How IMD found the beginning date of Kerala
The IMD predicted Kerala’s onset date using a locally developed statistical model that has been operational since 2005. It is fueled by six forecasts: minimum temperatures in northwest India; Peak pre-monsoon rainfall over the southern peninsula; Outgoing longwave radiation, or OLR, over the South China Sea and the southwest Pacific region; Low tropospheric winds over the southeast and northeastern Indian Ocean. OLR – total radiation emitted from the atmosphere into space – is an actual measure of cloudiness.
Regarding the weather elsewhere affecting the country at the moment, the agency said that a well-defined low pressure area over the southwest and central west adjacent to the Bay of Bengal persists, with an associated cyclonic circulation extending into the middle troposphere and tilting towards the southwest with height.
North-west and central India are likely to witness hot to intense heat wave on most days this week, even as heavy to very heavy rains are expected over northeast India and over Tamil Nadu, Puducherry, Karaikal, Kerala, Mahe and south interior Karnataka over the next three to four days.
