Heavy rain accompanied by gusty winds is set to sweep across large parts of Tamil Nadu beginning Thursday, 15 October, as a low-pressure area is expected to form over the Bay of Bengal, the Regional Meteorological Centre (RMC), Chennai has forecast. The rainfall is projected to intensify and spread further by Friday, 16 October, covering western, central, and delta regions of the state.

Thursday Forecast: Western and Southern Districts on Alert

On Thursday, heavy rain accompanied by winds of up to 50 kilometres per hour is expected to lash the hill areas of Coimbatore and Tirunelveli districts, along with Nilgiris, Erode, Salem, Theni, and Kanniyakumari. The forecast for this day is concentrated largely on western districts and parts of southern Tamil Nadu, according to the RMC.

Meanwhile, moderate rain is likely on Tuesday in Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, and Pudukkottai districts. Similar wet conditions have been forecast for Ramanathapuram, Thoothukudi, Tirunelveli, and Kanniyakumari, suggesting that southern coastal districts could experience rain ahead of the heavier spell expected later in the week.

Friday Forecast: Broader Spell Across Tamil Nadu

The rainfall footprint is expected to expand significantly by Friday, 16 October. Heavy rain has been forecast for Nilgiris, Coimbatore, Erode, Tiruppur, Salem, and Dharmapuri. The districts of Tiruchi, Ariyalur, and Perambalur are also expected to be affected, as are Madurai, Dindigul, Cuddalore, Kallakurichi, Namakkal, Karur, and Thanjavur.

In the Cauvery delta and adjoining areas, Tiruvarur, Mayiladuthurai, and Nagapattinam are expected to receive heavy rain. Pudukkottai and Sivaganga have also been included in the Friday forecast, underlining a broader spread compared to Thursday.

Chennai Temperatures and Northern Interior Warning

Notably, even as rain approaches, the weather centre has flagged a temporary rise in daytime temperatures in northern interior Tamil Nadu. Maximum temperatures in these areas could climb by up to three degrees Celsius through Thursday, the RMC said. Chennai's maximum temperature on Tuesday is expected to hover around 36 degrees Celsius, reflecting the warm conditions that continue to grip the northern parts of the state ahead of the low-pressure system's arrival.

What the Low-Pressure Formation Means

The projected Bay of Bengal low-pressure area is a seasonal weather feature typical of the northeast monsoon period, which governs Tamil Nadu's primary rainfall cycle from October through December. This comes amid an already active pattern, with southern coastal districts already receiving moderate showers. The RMC's district-wise outlook suggests differing weather conditions will prevail simultaneously across the state — moderate rain in the south and delta districts, warmer days in the north, and heavy rain spreading east and inland by Friday. Residents in the forecast districts, particularly those in low-lying and delta areas, are advised to remain alert to local administration advisories as the system develops.