Moderate rain accompanied by thunderstorms and lightning is expected across nine districts of Tamil Nadu on Thursday, 13 November 2026, as an atmospheric circulation over the Gulf of Mannar and adjoining areas drives rainfall towards the Cauvery delta and southern parts of the state. Simultaneously, the India Meteorological Department (IMD) has warned of a fresh low-pressure system forming over the Bay of Bengal by Friday, prompting fishermen to return to shore.

Districts Under Moderate Rain Alert

The weather department has identified Thanjavur, Tiruvarur, Mayiladuthurai, Nagapattinam, Pudukkottai, Ramanathapuram, Thoothukudi, Tirunelveli, and Kanyakumari as the nine districts likely to receive moderate showers with thunder and lightning during the day. These are predominantly coastal and agricultural zones, making the forecast particularly significant for farming communities and port operations.

Districts along the Western Ghats and the remaining parts of north coastal Tamil Nadu are expected to receive light rain on both Thursday and Friday. In Chennai, the forecast points to very light, localised showers rather than widespread rainfall across the metropolitan area.

Bay of Bengal Low-Pressure System: What IMD Said

The IMD has predicted the formation of a fresh low-pressure area over the Bay of Bengal on Friday, 14 November. According to the forecast, the system could further strengthen into a more pronounced low-pressure area by the same day. This developing system is distinct from the Gulf of Mannar circulation currently influencing Thursday's rainfall across Tamil Nadu, representing a second weather front that could affect the state in the days ahead.

Fishermen Directed to Return to Shore

The Tamil Nadu Fisheries and Fishermen Welfare Department has issued a directive asking all fishermen engaged in fishing operations in the Bay of Bengal to return to shore by Thursday night. The instruction is a precautionary measure ahead of the expected development and strengthening of the low-pressure system. Officials are focused on ensuring that fishing crews reach land safely before weather conditions over the Bay deteriorate.

What to Watch Going Forward

The dual weather developments — the Gulf of Mannar circulation and the anticipated Bay of Bengal low-pressure system — could together extend the spell of rainfall across Tamil Nadu into the weekend. Notably, the Cauvery delta districts, which are agriculturally sensitive during the kharif harvest season, are squarely in the forecast zone. Residents in the nine identified districts should remain alert to localised flooding risks, while coastal communities along the Bay of Bengal coastline should monitor IMD updates closely as the low-pressure system takes shape.