After a period of widespread thunderstorms, the intensity of rainfall across Tamil Nadu is expected to gradually decrease. However, scattered showers are set to continue, particularly over northern parts of the state, through the upcoming weekend. Forecasters predict a more significant reduction in rainfall, likely confined to just a few isolated spots, starting from September 22, 2025.
The past 24 hours, concluding at 8:30 a.m. on Friday, September 19, saw substantial rainfall in several areas of north Tamil Nadu due to an active Southwest monsoon. Villupuram recorded the highest accumulation with 19 cm, closely followed by Tirupattur which received 17 cm.
These weather patterns are influenced by a couple of key systems: an upper-air cyclonic circulation situated over the North Andaman Sea and adjacent Myanmar coast, and a trough extending across the central Bay of Bengal towards the southern Peninsular region. Thanks to these disturbances, Chennai experienced notably pleasant weather conditions throughout Friday, as confirmed by the Regional Meteorological Centre (RMC), Chennai.
A recent weather bulletin indicates that even some parts of south Tamil Nadu are likely to receive light to moderate rainfall. Isolated thunderstorms, accompanied by gusty winds, are also possible until Sunday, September 21. For Chennai residents, Saturday is expected to bring a day temperature of around 32 degrees Celsius, along with moderate rain in various localities.
B. Amudha, head (additional in-charge) of the RMC, explained, “Any weather systems that develop over the Bay of Bengal close to the south Peninsular region typically bring rainfall to Tamil Nadu. This daily thunderstorm activity is a common feature for Chennai during the Southwest monsoon period. Occasionally, the rainfall can even surpass initial forecasts due to the rapid formation of cumulonimbus clouds.”
Officials further noted that the state is likely to continue experiencing rainfall as a result of these existing weather systems and the ongoing transition phase of the Southwest monsoon’s withdrawal. Looking ahead, the Meteorological department has also issued a forecast for a low-pressure area, which is anticipated to form over the northeast Bay of Bengal after September 25.