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Chennai: Tamil Nadu’s lifeline, Northeast monsoon (NEM), on Monday withdrew completely from South India, after being active since its onset on October 15, 2024, the third longest monsoon in about a century.
The state and Puducherry received 614.2 mm of rainfall during the NEM against the average rainfall of about 445 mm. While 589.9 mm of rainfall was recorded between October 1 and December 31, 2024, the remaining 24.3 mm of rainfall was registered in the first 27 days of January 2025.
The NEM season is normally between October and December but it spills over to January as well. However, this is only the third delayed withdrawal for the monsoon since 1871, since when records are available, after January 28 in 1933, and January 30 in 1926, weather bloggers said.
The trend of the NEM withdrawing late and extending into mid-January was noticed in 2021, and 2022 as well, though late withdrawal of the monsoon isn’t a “very rare event.” NEM 2024 was a beneficial year for the whole of Tamil Nadu with as many as 27 districts receiving excess rains, while the remaining 12 experiencing near normal rain for the year.
The Indian Meteorological Department (IMD) said on Monday that no significant rainfall activity over the southeast peninsula during the past two days, and in the lower levels, dry winds from northern India are prevailing over the region.
“Considering the above points, the Northeast Monsoon rains have ceased over Kerala-Mahe, South Interior Karnataka, Tamil Nadu-Puducherry-Karaikal, Rayalaseema and adjoining areas of Coastal Andhra Pradesh & Yanam from today,” the IMD added.
K Srikanth, an independent weather blogger, said late withdrawal of Northeast Monsoon is almost a recurring event in years with La Nina influence. “In La Nina years, the withdrawal probability is higher. The rains that Tamil Nadu and Puducherry received in January 2025 is seventh highest since 2000 and 43rd highest since 1871,” Srikanth told DH.
He said “unseasonal" rains in January were due to the influence of La Nina as many factors come into play. “If you take January, the rainfall occurred with a gap of a few days. We count NEM as only between October and December and the rainfall in January is counted as winter rains,” he added.
Another weather blogger Pradeep John said the combined storage of reservoirs that supply water to Chennai has touched 12 tmcft, the best ever storage levels at the end of January.
NEM is the chief 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.