The India Meteorological Department (IMD) has forecast rain across 12 districts in Tamil Nadu on Sunday, 12 October 2025, driven by an upper-air cyclonic circulation persisting over the Gulf of Mannar and the adjoining southern Tamil Nadu coast. The system is positioned approximately 0.9 kilometres above mean sea level and is influencing weather conditions across the state's western, southern, and coastal belts.

Districts in the Rain Zone

The districts identified for Sunday's showers include Nilgiris, Coimbatore, Dindigul, Virudhunagar, Madurai, Sivaganga, Ramanathapuram, Thoothukudi, Theni, Tenkasi, Tirunelveli, and Kanniyakumari. Residents in these areas can expect moderate spells of rain accompanied by strong winds, according to the weather department.

The IMD has separately flagged the possibility of heavy rain in the hilly areas of Coimbatore district and in the Nilgiris and Theni districts, placing special emphasis on the western hill belt where intensity could exceed moderate levels elsewhere.

Monday Outlook: Seven Districts Remain Affected

For Monday, 13 October, the forecast narrows to seven districts — Nilgiris, Coimbatore, Erode, Kanniyakumari, Tirunelveli, Thoothukudi, and Tenkasi — all within the western belt and southern tip of the state. Notably, Erode enters Monday's list while several districts from Sunday's forecast, including Madurai, Sivaganga, and Ramanathapuram, are not included.

Northern Interiors Brace for Above-Normal Heat

In contrast to the wet conditions expected in the south and west, northern interior Tamil Nadu faces a different challenge. The IMD has warned that maximum daytime temperatures in these areas could remain three degrees Celsius above normal until at least Wednesday, 15 October. The temperature alert applies specifically to daytime maximums and does not signal a uniform statewide rise.

Why the Divergence Matters

The simultaneous rain-and-heat alert reflects Tamil Nadu's complex micro-climatic geography. The state's western ghats and coastal zones routinely receive the first influence of weather systems forming over the Bay of Bengal and the Gulf of Mannar, while the northern plains often remain dry and warmer under different pressure gradients. This comes amid the transition between the southwest and northeast monsoon seasons, a period when such split weather patterns are common across peninsular India. Residents in rain-flagged districts — particularly those in hill areas — are advised to remain alert to the possibility of localised flooding or landslides during heavy spells.