Tamil Nadu receives above-average rainfall, thanks to hyper-active monsoon

Chennai: Tamil Nadu’s lifeline, North-east Monsoon (NEM), which is likely to withdraw completely from the state by mid-January, has dumped 33 per cent more rainfall than the normal average from October to December 2024. The state and Puducherry received 589.9 mm of rainfall in 2024 during the NEM against the average rainfall of 442.8 mm. 

Chennai, the capital city, had a beneficial year for the fifth consecutive year as it received 1,077.6 mm of rainfall between October and December, which is an increase of 33.9 per cent. The excess rains have ensured that all reservoirs that supply drinking water to the city brim with water.

The water capacity at Chembarambakkam as on December 31, 2024 stood at 3,645 mcft, followed by Red Hills (3,300 mcft), Poondi (3,231 mcft), Cholavaram (1,081 mcft), and Veeranam (1,465 mcft). The combined water level at the five reservoirs stood at 11,296 mcft against the full capacity of 12,722 mcft which is 89 per cent storage.

“There won’t be any water problem in 2025 for Chennai, Kanchipuram, Tiruvallur, and Chengalpattu districts. Rains have come as a blessing to Chennai for the last five years. Generally, one doesn’t see the monsoon on a 5-year-streak. It has always been erratic,” Pradeep John, an independent weather blogger, said.

Not just storage of water in reservoirs, the ground water in Chennai has also recharged well. “We can keep the water level in reservoirs that supply drinking water to Chennai close to brim even till March or April,” John added. Chennai suffered its worst-ever water crisis in 2019 but good rains since 2020 have ensured that the city doesn’t suffer due to non-availability of water.

Of the 39 districts, as many as 27 districts received excess rains in 2024, while the remaining 12 experienced near normal rain for the year. The NEM will officially withdraw from the state in mid-January after Pongal.

"Active easterly winds was one of the reasons for the above-average rainfall in Tamil Nadu. Though the number of cyclones formed this year is just four compared to six in 2023, the state received excess rainfall under the influence of low-pressure areas,” S Balachandran, Director, Regional Meteorological Centre (RMC), Chennai, said.

K Srikanth, a weather blogger, said only two districts -- Thoothukudi and Nilgiris -- didn’t record above average rainfall during NEM and that this is the fifth consecutive year that Tamil Nadu and Puducherry have registered above average rainfall.

“This is the 11th best year overall since 1871 and sixth best year in the last 30 years. In the past 20 years, TN and Puducherry recorded more than average rainfall for 14 years,” Srikanth added.

NEM is the main rainy season for Chennai and Tamil Nadu, even as high intense rainfall in less duration has become the order of the day as the state witnesses an increase in the number of extreme weather events. While the number of hot days are increasing, the number of rainy days are on the decline, though the average rainfall is also increasing.