The Chennai rain forecast has intensified for the next few days, with the India Meteorological Department warning of moderate spells across the city and nearby districts, heavy rain in Tiruvallur on Saturday, and possible thunderstorms, lightning and gusty winds between September 17 and 18.
The IMD has forecast moderate rain at one or two places in Chennai, Tiruvallur, Chengelpet, Kancheepuram and other parts of north Tamil Nadu and the interior districts on Thursday and Friday. Rain activity follows several days of short, isolated spells across the region.
V R Durai, director of the Area Cyclone Warning Centre, said an upper-air circulation over south coastal Andhra Pradesh and adjoining Rayalaseema, together with a trough extending from north interior Karnataka to the Gulf of Mannar, could bring rain to Chennai, neighbouring districts and other parts of Tamil Nadu.
An upper-air circulation is an area where winds rotate around a region of relatively low pressure several kilometres above the ground. It can draw moisture into the atmosphere and encourage air to rise, allowing clouds to form when conditions are favourable. A trough is an elongated zone of relatively low pressure that can also support rising air and cloud formation.
The IMD said the rain may not be widespread across Chennai, but moderate spells could occur in some areas until September 20. On Thursday, the city and suburbs may receive light to moderate rain during the evening and night, with partly cloudy skies. Daytime temperatures are expected to remain between 35°C and 36°C, while nighttime temperatures may stay around 27°C to 28°C.
Thunderstorms and lightning, accompanied by gusty winds reaching 40-50 kmph, may occur in some areas on September 17 and 18. The forecast places Tiruvallur under a higher rain risk, with heavy rain expected there on Saturday.
The rainfall distribution since June 1 shows that several districts remain below their normal totals, although readings vary significantly within Chennai. The city has recorded 361.4mm of rain, around 2% below normal. Nungambakkam has received 392.7mm, about 10.7mm above normal, while Meenambakkam recorded 422.4mm, around 6.1mm below normal.
The wider northern Tamil Nadu region has seen larger deficits. Tiruvallur has recorded 86.3mm, 22% below normal; Kancheepuram has received 264.6mm, 33% below normal; and Chengelpet has recorded 154.5mm, 54% below normal.
The current forecast therefore combines uneven seasonal rainfall with the possibility of short, intense spells and strong winds. The IMD’s forecast period extends through September 20, with heavy rain specifically indicated for Tiruvallur on Saturday.
