After a spell of widespread thunderstorm activity, the intensity is likely to ease, with scattered rainfall continuing particularly over north Tamil Nadu until the weekend. A gradual dip in rainfall, which may be confined to one or two places, is expected over the State from September 22, 2025.

The vigorous Southwest monsoon brought in heavy downpour over many places in north Tamil Nadu during the past 24 hours ending 8.30 a.m. on Friday (September 19). Villupuram recorded the highest rainfall of 19 cm for the day, followed by Tirupattur with 17 cm.

The prevailing weather systems -- an upper air cyclonic circulation over North Andaman and adjoining Myanmar coast, and a trough running across central Bay of Bengal over south Peninsular region -- will influence rainfall. Chennai enjoyed pleasant weather on Friday owing to these multiple weather disturbances, according to the Regional Meteorological Centre (RMC), Chennai.

According to a weather bulletin, parts of south Tamil Nadu are also likely to receive light to moderate showers. Thunderstorms with gusty winds may occur in isolated places till Sunday (September 21). Chennai may experience a day temperature of 32 degree Celsius and receive moderate rainfall in some areas on Saturday.

"Weather systems forming anywhere over the Bay of Bengal near the south Peninsular region are likely to bring rainfall to Tamil Nadu. Such daily thunderstorm activity over Chennai is common during the Southwest monsoon. At times, the rainfall intensity exceeds the forecast levels due to the sudden development of cumulonimbus clouds within a short span," said B. Amudha, head (additional in-charge), RMC.

The State may continue to receive rainfall due to the weather systems and the transition phase of the Southwest monsoon withdrawal, officials said. Meanwhile, the Meteorological department has forecast that a low pressure area is likely to form over northeast Bay of Bengal after September 25.

Scattered showers to continue over T.N. until September 21