The northeast monsoon is likely to set in over the southern peninsula in the next two-three days, with a prolonged spell of rain expected across the region over the subsequent five-six days, the India Meteorological Department (IMD) said on Monday.
In its daily forecast, the weather department said conditions are favourable for the onset of the northeast monsoon, while the southwest monsoon continues to withdraw from the remaining parts of the country.
"Isolated heavy rainfall is expected over Kerala and Mahe, coastal and south interior Karnataka, Tamil Nadu, Puducherry and Karaikal, and coastal Andhra Pradesh during 15-18 October," said the IMD.
"North interior Karnataka is likely to receive isolated heavy rainfall on October 17 and 18, while Rayalaseema may experience similar conditions on October 15 and 16," the weather department added.
India experiences two major monsoon seasons — the southwest monsoon, which lasts from June to September, and the northeast monsoon, also known as the retreating monsoon, which occurs from October to December and primarily affects peninsular India.
The southwest monsoon typically arrives in Kerala on the southwestern coast around June before advancing across the country. It is the primary monsoon system affecting India, bringing relief from the heat and contributing significantly to the country's ecosystem and economy, particularly the cultivation of kharif crops.
The northeast monsoon, although less intense than the southwest monsoon, is crucial for the growth of rabi crops.
Southwest monsoon ends with 12.6% rainfall deficit
This year's southwest monsoon ended with 759.4 mm of rainfall, 12.6 per cent below the normal of 868.6 mm, according to the IMD.
One of the key reasons behind the rainfall deficit has been the prevailing El Nino conditions over the tropical Pacific, which emerged in June and have been gaining strength since.
El Nino is one of the three phases of the El Nino Southern Oscillation (ENSO), a climate phenomenon characterised by changes in sea temperatures along the central and eastern tropical Pacific Ocean, accompanied by fluctuations in the atmosphere overhead.
While El Nino is associated with reduced monsoon rainfall in India and a warming effect on the planet, its opposite phase, La Nina, usually results in a cooling effect. ENSO also has a neutral phase.
Global weather agencies, including the World Meteorological Organization (WMO), have predicted that this year's El Nino event is likely to peak in December 2026 and could become the strongest since observations began in 1950.
The El Nino conditions are also expected to persist through February 2027.