“The cyclonic circulation lies over southwest Bay of Bengal off north Tamil Nadu coast at 7.6 km above mean sea level. A low-pressure area is likely to develop over northeast Bay of Bengal and the neighbouring area around September 20,” said a source from the Regional Meteorological Department, Chennai.

Chennai saw maximum temperatures of 33.6 and 33.2 degrees Celsius at Nungambakkam and Meenambakkam respectively, and minimum temperatures of 27.7 and 26.6 degrees. Light to moderate rainfall is expected in districts such as Tiruvallur, Vellore, Ranipet, Tirupattur, Krishnagiri, Dharmapuri, Tiruvannamalai, Villupuram, Kallakurichi, Salem, Kancheepuram, and Chengalpattu. “While Monsoon picks up in Kerala and West Coast again, the next two days look good for north Tamil Nadu, with improved steering and convergence right over north TN. Vellore, Chennai, Tiruvallur, Kancheepuram, Chengalpat Salem-Namakkal, Dharampuri, Tirupattur, Ranipet, Tiruvannamalai, all likely to fall in the path of convergence,” said Pradeep John, who runs the Facebook page Tamil Nadu Weatherman. Thunderstorms are expected over the next 24 to 48 hours, with maximum temperature at 34 degrees and minimum temperature at 27 degrees. Heavy rains are also predicted over the Ghat areas on September 20 and 21, according to met officials.