The northeast monsoon is likely to hit Tamil Nadu by the end of October, and is predicted to result in above-average rainfall in most of the state, the IMD’s Regional Meteorological Centre (RMC) announced on Wednesday.

The RMC, in the statement, also said that 18 districts of Tamil Nadu will receive heavy rains till October 5 and issued a yellow alert in these districts.

Heavy rains are likely for the next three days in the Ghat areas of Coimbatore district, Nilgiris, Erode, Krishnagiri, Dharmapuri, Salem, and Tirupattur districts, while light to moderate rains are likely in north coastal districts, including Chennai and adjoining districts of Tiruvallur, Chengalpattu, and Kancheepuram, it predicted.

The weather office stated that the rains would be accompanied by thunderstorms and attributed them to a cyclonic circulation prevailing over the Camorin area and adjoining equatorial Indian Ocean.

Forecasting that the state is likely to receive above-average rainfall during the northeast monsoon, it said that rains would be heavy in many parts of northern Tamil Nadu during the monsoon.

RMC’s Cyclone Centre Director, P. Senthamarai Kannan said: “From October to December during the northeast monsoon, the system is likely to range from normal to slightly above normal levels. Additionally, the southern districts, including Kanyakumari and Thoothukudi, are expected to receive normal to below normal levels.”

He also said that as the southwest monsoon is yet to recede, the exact dates of the northeast monsoon so could not be announced.

The official said that in October, the Western Ghats areas including Tiruppur and Nilgiris are likely to receive above-normal rainfall.

The RMC also said that during the southwest monsoon from June 1 to September 30, the state received 18 cm excess rainfall.

In December 2023, during the northeast monsoon, unprecedented rainfall and water logging were witnessed in both the northern and southern districts of Tamil Nadu. This led to a series of tragic events and widespread destruction and the state capital was inundated by floods. Four districts of southern Tamil Nadu witnessed heavy downpours and 35 people died.

The Tamil Nadu State Disaster Management Authority (TNSDMA) reported that Chennai district witnessed an average of 400 mm rainfall during December 3-5. Similarly, Kalyanapattinum in Thoothukudi district witnessed heavy downpours in December 2023 due to northeast monsoons and some cyclonic systems. In 2015, Chennai received heavy rainfall inundating the city leading to the loss of lives of 290 people.

The TNSDMA is gearing up for any eventuality this year.