Northeast Monsoon Triggers Heavy Rains Across Tamil Nadu and Chennai

The Northeast monsoon has entered a vigorous phase, bringing heavy overnight rainfall to Tamil Nadu, especially across north coastal districts and Chennai. A low-pressure area formed over the southwest Bay of Bengal off the coast of Tamil Nadu during the early hours of Wednesday, October 21. A weather trough extends from this low-pressure center across the adjoining Tamil Nadu coast to north coastal Andhra Pradesh. This wet spell is expected to continue until October 26.

Heavy Rainfall

Rainfall measurements across Chennai showed MGR Nagar topping the charts with 15 cm in the 24-hour period ending Wednesday morning. Vadapalani recorded 14 cm of rain, while Saidapet, Meenambakkam, Alandur, and Kancheepuram each received 13 cm. Areas such as the DGP office, Madipakkam, Valasaravakkam, and Maduravoyal recorded 12 cm, with Nungambakkam, Nerkundram, and Adyar logging 11 cm. Korattur registered 10 cm, and Ambattur, Saligramam, Puzhal, R.A. Puram, Ayapakkam, YMCA Nandanam, Parrys, Anna University, Manali, Anna Nagar West, and Pozhichalur each recorded 9 cm. Other districts including Kanniyakumari, Tiruppur, Ramanathapuram, Tenkasi, and Virudhunagar also experienced moderate to heavy showers.

Weather Systems

The Regional Meteorological Centre in Chennai reports that another low-pressure area over the southwest Arabian Sea is moving toward the Somalia coast and will likely have no major impact on Tamil Nadu. However, the agency notes that a fresh low-pressure area is brewing over the southeast and adjoining east-central Bay of Bengal around October 23. Southern and delta districts, including Thoothukudi, Tirunelveli, and Kanniyakumari, face forecasts of very heavy rainfall until Thursday morning, while Karur, Dindigul, Pudukottai, and Thanjavur expect heavy downpours.

Context

The Northeast monsoon is a crucial seasonal weather pattern that brings the bulk of the annual rainfall to southern peninsular India, particularly Tamil Nadu, between October and December. Multiple low-pressure systems forming sequentially over the Bay of Bengal are common during this peak monsoon window, frequently causing widespread waterlogging in urban centers like Chennai.