Almost entire Kerala, adjoining South Interior Karnataka and southern, central and west Tamil Nadu may receive heavy to very rain (in orange shade) this week, according a ECMWF outlook. | Photo Credit: www.windy.com

The north-east monsoon is gathering strength over the South Peninsula, with isolated heavy rainfall likely over Kerala and Mahe and South Interior Karnataka for next six days until Saturday, and over Coastal Andhra Pradesh, Yanam and Rayalaseema for three days until Wednesday, India Meteorological Department (IMD) has said.

The 24 hours ending Sunday morning saw extremely heavy rainfall of 21 cm or more over Tamil Nadu, while Coastal Andhra Pradesh, Rayalaseema, Telangana and South Interior Karnataka received heavy rain of 7-11 cm. The core of rainfall activity is now expected to shift towards Kerala and South Interior Karnataka this week.

Cyclonic circulations and a trough are working in tandem to sustain widespread moisture over the South Peninsula. On Sunday afternoon, one circulation lay over west-central Bay of Bengal and adjoining coasts of south Andhra Pradesh and Tamil Nadu, while another persisted over North Interior Karnataka. A trough extended from Lakshadweep to the west-central Bay across Karnataka and south Andhra Pradesh.

Meanwhile, a low-pressure area has developed over south-west Arabian Sea, more than 2,300 km off Kerala coast, and may intensify another round by Monday. Its distance makes an immediate impact on southern India’s weather unlikely. Global forecasts, however, point to the possibility of a successor system developing closer to home over Lakshadweep later this week, in response to an evolving system over the Bay of Bengal. 

The IMD on Sunday flagged an upper-air cyclonic circulation over the Gulf of Thailand, backed by super typhoon Champi currently approaching the Philippines and watching from behind. The incoming circulation is expected to move into Andaman Sea, descend to lower atmospheric levels and consolidate into a ‘low’ over the Bay.

The IMD’s numerical weather model indicate the circulation could intensify by a couple of notches October 28 (Saturday). The European Centre for Medium-Term Weather Forecasts suggest that, from this position, it could draw in westerly flows from the Arabian Sea system and help strengthen the brewing twin circulation there. The IMD, however, does not appear to share that assessment, leaving the Arabian Sea system without significant projected escalation at least in its current outlook. 

The Madden–Julian Oscillation (MJO), a large-scale pulse of enhanced tropical convection that travels eastward from Africa across the Indian Ocean, may be adding further impetus. By influencing distribution of moisture, clouds and rising air, the MJO can help create conditions favourable for ‘low’s, depressions and cyclones, while also influencing monsoon activity. The ECMWF has indicated a strong MJO event over the Indian Ocean, a signal worth watching as the north-east monsoon settles into its active phase.

Strengthening trade winds over equatorial Africa and the Indian Ocean since early September also point to the possible emergence of a positive Indian Ocean Dipole (+IOD). A positive IOD can alter convection and moisture transport, potentially supporting northeast-monsoon, although its effects on rainfall over Tamil Nadu are not automatic. Farther east, El Niño conditions persist over the equatorial Pacific.

The combined influence of El Niño, the evolving IOD and tropical convection could shape the coming weeks, but the outcome for South India will depend on how these large-scale signals translate into the position, movement and persistence of individual rain-bearing systems. The US Climate Prediction Center expects the Bay and Arabian Sea to remain active into the final week of October and possibly early November.

That outlook keeps the prospect of further tropical disturbances alive, though, at least for now, without a cyclone that could alter wind flows and rainfall distribution. Broader signals offer grounds for cautious optimism, but not a guarantee of a wet season across every district. For Tamil Nadu and the wider South Peninsula, the crucial test is whether troughs and disturbances deliver repeated, well-distributed rain that replenishes soil moisture, tanks and reservoirs, rather than dump too much rain in intense spells. 

Published on October 18, 2026