Chennai heavy rain is likely over the weekend, with the Regional Meteorological Centre forecasting heavy showers in the city and several other Tamil Nadu districts on October 18 and 19. Rainfall is expected to continue across the state until October 26, with thunderstorms and lightning accompanying showers in several regions.
VR Durai, director and senior atmospheric scientist at the RMC in Chennai, said the rainfall over Chennai and neighbouring districts was being influenced by two upper-air cyclonic circulations. One is located over north Tamil Nadu and adjoining south coastal Andhra Pradesh at an altitude of 4.5 km to 5.8 km above mean sea level. The second extends from the northern parts of Lakshadweep to the southwest Bay of Bengal across Kerala and Tamil Nadu, between 1.5 km and 3.1 km above mean sea level.
The RMC has forecast heavy rain in Chennai and other parts of Tamil Nadu during the weekend. Moderate rain with thunderstorms and lightning is expected at many places across the remaining parts of the state, Puducherry and Karaikal until October 23. The forecast places the maximum temperature at around 33 degrees Celsius and the minimum at around 24 degrees Celsius under cloudy skies. Maximum temperatures are expected to remain near normal across Tamil Nadu, Puducherry and Karaikal until October 21.
The weather system is expected to produce heavier rainfall in the state’s southern and hilly districts. On October 20, heavy to very heavy rain accompanied by thunderstorms and lightning is likely at isolated places in The Nilgiris, Coimbatore, Tirupur, Dindigul, Theni, Tenkasi, Virudhunagar, Tirunelveli and Kanniyakumari.
Heavy rain is also likely in Madurai, Tiruchy, Salem, Namakkal, Erode, Karur, Sivaganga, Ramanathapuram, Thoothukudi and Pudukkottai. Durai said the Ghat districts, adjoining areas and southern districts were likely to receive more rain than the northern coastal districts.
The timing of rainfall may vary by weather system. Durai said northeast monsoon showers were likely mainly during the evenings and around midnight, while low-pressure systems could bring rain during the daytime. This pattern could affect daily travel and outdoor activity across Chennai and other urban areas, particularly during periods of thunderstorms and lightning.
Tamil Nadu had already recorded significant rainfall on October 17. Uthiramerur in Kancheepuram district received 15 cm, while Perambalur recorded 12 cm. Puducherry, Chengam in Tiruvannamalai and Ponparappi in Kallakurichi received 10 cm each. Perambur and Madhavaram in Chennai, along with Mugaiyur in Villupuram, recorded 9 cm each.
The RMC said rainfall across Tamil Nadu would remain active through the coming days. Its forecast places the next significant period of heavy rain on October 20, while moderate rain and thunderstorms are expected to continue across the state, Puducherry and Karaikal until October 23.
