Thick rain-bearing clouds enveloped parts of south-east Tamil Nadu and adjoining south-west Bay of Bengal as well as the Lakshadweep Islands on the Arabian Sea side by Wednesday evening | Photo Credit: www.windy.com

A fresh low-pressure area over the south-west Bay of Bengal off the Tamil Nadu coast is likely to set the stage for another spell of intense north-east monsoon rain from the weekend and into early next week. Tamil Nadu and Puducherry, Coastal Andhra Pradesh and Yanam, Kerala and Mahe, and Lakshadweep are in the firing line as moisture-laden systems threaten to unleash widespread showers, with isolated bouts of very heavy rain.

The India Meteorological Department (IMD) has forecast isolated very heavy rainfall of 11–20 cm over Tamil Nadu, Puducherry and Karaikal for three days from Thursday. Kerala and Mahe are in for similar spells on Thursday and again on Saturday and Sunday, while Lakshadweep faces the prospect on Friday and Saturday. The forecast also flags isolated heavy rainfall of 7–11 cm over South Interior Karnataka for four days from Thursday. Kerala and Mahe could see heavy spells on Friday and again on Monday and Tuesday; Lakshadweep on Thursday and Sunday; and Tamil Nadu, Puducherry and Karaikal on Monday.

The impending wet spell follows a punishing 24 hours in which heavy to very heavy rain, exceeding 10 cm in several places, battered parts of Tamil Nadu, Puducherry and Karaikal, Rayalaseema, and Kerala and Mahe. MGR Nagar in Chennai topped the charts with 15 cm, followed by Chennai airport and Alandur with 13 cm each. The DGP Office in Chennai and Colachel in Kanyakumari district recorded 12 cm apiece, while Chennai city, Kollam in Kerala and Tada in Tirupati district received 11 cm each. Aliyar in Coimbatore rounded off the list with 10 cm.

The larger atmospheric setting is also falling into place for a vigorous rain spell. A favourable pulse of the Madden–Julian Oscillation (MJO) appears to be working in tandem with the positive phase of the Indian Ocean Dipole (IOD), helping propel circulations into the South Peninsula towards a weekend crescendo. Together, the two climate drivers appear to have displaced El Niño-induced suppression and the dry spell to the Maritime Continent around Indonesia, at least for now. These conditions that sat heavy over the Arabian Sea and the Bay of Bengal had contributed to a destructive dry spell, hastening the demise of the preceding south-west monsoon.

Both the Bay and the Arabian Sea are now awash with moisture and cloud, leaving the South Peninsula favourably positioned to receive repeated rounds of rain. An expansive wet spell is shaping up for the remainder of the week and early next week, as the newly formed low is expected to move across the southern tip of the peninsula and emerge over the south-east Arabian Sea, off Kerala and around Lakshadweep.

The projected journey nearly recalls the circuitous track of the system that preceded very severe cyclonic storm Ockhi in November 2017. Ockhi, which reached Category 3 intensity on the Saffir–Simpson hurricane wind scale, developed from a ‘low’ that moved around Sri Lanka into the region. The cyclone devastated parts of the coasts of Sri Lanka and Kerala before speeding towards the Gulf of Cambay in Gujarat and weakening over land.

The parallel is a reminder of the region’s capacity for rapid weather developments, rather than an indication that the present system is destined to follow the same course or intensity. Closer to the ground, the IMD has issued a very heavy rainfall alert for Thiruvananthapuram, Kollam, Pathanamthitta, Alappuzha and Kottayam districts of south and central Kerala until Thursday morning.

The developing low had already begun laying down its cloud bands on Wednesday evening. Stretching inland from the south-west Bay, the rain-bearing bands swept across Chennai, Tindivanam, Cuddalore, Neyveli, Kumbakonam, Mannargudi, Pudukkottai and Karaikudi in Tamil Nadu, extending westwards into Thiruvananthapuram and Kollam in neighbouring Kerala. A little over 500 km to the west, thick, rain-laden clouds hovered over Minicoy in Lakshadweep and extended northwards towards Kavaratti, signalling that the Arabian Sea flank of the developing weather system was also coming into play.

The eastern Bay is stirring yet again, raising prospect of a fresh round of weather activity. A cyclonic circulation over the Gulf of Thailand and adjoining parts of Thailand and Myanmar is expected to emerge over the north Andaman Sea and organise into a ‘low’ over the south-east and adjoining east-central Bay by Friday. The system may initially head towards the Tamil Nadu–Andhra Pradesh coasts before intensifying further.

Meanwhile, the western Pacific is contending with a much more powerful storm. Category 5 super typhoon Champi with wind speeds of 290 km/hr is forecast to pass dangerously close to the northern Philippines, with Taiwan to its north-west, also keenly watching its progress. The storm is expected to weaken substantially, potentially to Category 1 intensity by Sunday, as it moves past Taiwan towards East China Sea. Its projected weakening notwithstanding, the close passage poses a significant weather threat to areas along its path.

Published on October 21, 2026