CHENNAI: After nearly three weeks of subdued activity, the northeast monsoon is set to regain vigour over Tamil Nadu from this weekend, with the Regional Meteorological Centre (RMC), Chennai, forecasting widespread rainfall across coastal districts between November 17 and 20.
According to the RMC, light to moderate rain is likely to continue at isolated places till November 15, before becoming more widespread thereafter. Heavy rainfall is expected at isolated locations over Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, Cuddalore, Villupuram, Chengalpattu and Puducherry on November 17, with similar activity predicted over parts of the delta and coastal districts the following day.
The revival comes after an unusually dry start to November. Tamil Nadu, which normally receives around 181.7 mm of rainfall during the month, has so far recorded only 15.1 mm till November 10 — one of the weakest starts in recent years. For comparison, the state received 425 mm in 2021, 233 mm in 2023 and 140 mm in 2024 during the same period.
The deficit has been particularly pronounced across the delta and north coastal belts. Even Chennai, which usually benefits from sea-borne showers, has seen only intermittent drizzles since late October. “Southern districts such as Ramanathapuram, Thoothukudi and Tirunelveli have received occasional spells, but the stretch between the Delta and North Tamil Nadu has remained largely dry,” official data indicated.
Meteorologists attribute the lull to natural intra-seasonal variations typical of the northeast monsoon. As per the India Meteorological Department’s (IMD) climatological studies, these active and weak phases are influenced by large-scale atmospheric waves and equatorial wind patterns.
P Senthamarai Kannan, Director, Area Cyclone Warning Centre, RMC, said, “Light to moderate rain will occur at isolated places till November 15. Thereafter, rainfall activity is set to increase, becoming widespread over coastal districts from November 16.”
Mahesh Palawat, vice president (meteorology and climate change), Skymet Weather, observed that the monsoon had struggled to pick up momentum due to the absence of strong weather systems over the Bay of Bengal.
“Cyclone Montha tracked towards the Andhra coast, while a few weak upper-air circulations failed to drift towards Tamil Nadu,” he said. “These shallow systems disturbed the north-easterly flow from the Bay — the very winds that sustain the monsoon. Consequently, rains have remained patchy and confined to the southern districts. Moreover, during La Niña years, monsoon performance tends to fall below normal as large-scale atmospheric patterns become less conducive for rain-bearing systems over the southern peninsula. However, some revival is expected from November 17.”
Weather blogger K Srikanth sounded optimistic about a strong rebound later this month. “The monsoon is gearing up for its second power play of the season,” he noted in his post. “A developing east–west shear zone is expected to trigger widespread rains from mid-next week. If this materialises, the Delta and North Coastal districts, including Chennai and Chengalpattu, could recover from the current deficit and possibly move into the excess category by the end of November. Another circulation from the Andaman Sea later this month may keep the monsoon active into early December, though model consistency will need close watch.”
Top rainfall deficit districts (Oct 1 – Nov 12, 2025)
(Percentage departure from normal rainfall during the Northeast Monsoon)
District Actual (mm) Normal (mm) Departure (%)
Nagapattinam 227.0 440.6 –48%
Karaikal 322.7 499.7 –35%
Tiruppur 138.4 210.3 –34%
Perambalur 163.4 247.5 –34%
Mayiladuthurai 301.4 430.2 –30%
Karur 139.3 192.9 –28%
Salem 164.7 223.0 –26%
Thanjavur 250.3 286.3 –13%
Pudukottai 178.2 205.2 –13%
Dindigul 193.6 285.9 –32%