According to the seven-day forecast, Chennai is likely to record maximum temperatures of 36 degrees Celsius to 37 degrees Celsius on May 17, with the mercury expected to rise further to 39 degrees Celsius by May 20.

The RMC weather bulletin said a trough extends from the centre of a wellmarked low-pressure area over the southwest and adjoining west-central Bay of Bengal to south Madhya Maharashtra across north Tamil Nadu at less than one kilometre above mean sea level. Deputy Director General of Meteorology, RMC, VR Durai said the well-marked low-pressure area over southwest and adjoining west-central Bay of Bengal was expected to move northeastwards and weaken over the next three days.

“As cloudiness decreases, mercury is likely to rise over coastal TN, including Chennai,” he said.

Weather blogger Pradeep John, popularly known as Tamil Nadu Weatherman, said hot conditions were expected to intensify in Chennai and northern districts from May 17 to May 27.

“Hot and sizzling days are expected to return to Chennai, Vellore, Ranipet, Tirupattur and Villupuram. This will be the hottest period for Chennai and the nearby districts bordering Andhra Pradesh. Chennai has been recording 35-36°C over the past few days, and temperatures may rise to around 41-42°C next week,” he said.

He said isolated rainfall activity was likely to resume in interior districts of TN from May 18.

The RMC bulletin said light to moderate rain accompanied by thunderstorms and lightning was likely at isolated places over Tamil Nadu, Puducherry and Karaikal on May 15 and May 16.

Heavy rainfall is likely at isolated places in the ghat areas of Coimbatore and the Nilgiris, besides southern districts including Madurai, Theni and Dindigul, on May 15.