CHENNAI: After a week of hot and dry weather, Chennai and its neighbouring areas, along with over 20 districts in Tamil Nadu, are expected to receive moderate rain accompanied by thunderstorms, lightning, and gusty winds reaching speeds of 40-50 kmph at isolated places on Friday.

The Regional Meteorological Centre (RMC) has forecast heavy rain at isolated places in The Nilgiris and Coimbatore districts on Friday.

According to the weather bulletin, a trough extending from a cyclonic circulation over Marathwada and its neighbourhood to the Gulf of Mannar, across Interior Karnataka and Tamil Nadu at 0.9 km above mean sea level, is driving the rain across the State.

Moderate rain with thunderstorms, lightning, and gusty winds reaching 40-50 kmph is expected at a few places over the remaining Western Ghats districts, Chennai, Tiruvallur, Chengalpattu, Kancheepuram, Ranipet, Vellore, Tirupattur, Salem, Tirupur, Erode, Dharmapuri, Namakkal, Madurai, Sivagangai, Krishnagiri, Kallakurichi, Cuddalore, Perambalur, Ariyalur, Karur, Mayiladuthurai, Thanjavur, Tiruvarur, Nagapattinam, and Pudukottai districts, as well as Puducherry and Karaikal.

On September 19, heavy rain is likely at isolated places over Nilgiris, Coimbatore, Dharmapuri, Krishnagiri, Vellore, Villupuram, Tiruvannamalai, Tirupattur, Ranipet, Tiruvallur, Kallakurichi, and Salem districts. The heavy spell will continue at isolated places over The Nilgiris, Coimbatore, Dindigul, Dharmapuri, Krishnagiri, Tiruchirappalli, Ariyalur, Perambalur, Madurai, Villupuram, and Kallakurichi districts on September 20.

For Chennai, light to moderate rain with thunderstorms and lightning is likely in some areas during the evening or night on Friday. The maximum temperature in the city will hover around 37 degrees Celsius, while the minimum will be around 26 degrees Celsius.

Maximum temperatures are likely to remain near normal across Tamil Nadu, Puducherry, and Karaikal until September 21. Moderate rain at a few places, along with thunderstorms and gusty winds reaching 40-50 kmph at isolated spots, will continue over the Western Ghats districts, North Coastal Tamil Nadu, Puducherry, and Karaikal on September 22 and 23.