Continuous rain is occurring in Chennai due to the formation of a low-pressure system over the Bay of Bengal, which is typical during the Northeast Monsoon season.
| Photo Credit: Ragu R.
The well-marked low pressure area over the Bay of Bengal is set to retain the same intensity and is unlikely to strengthen further. The Regional Meteorological Centre has forecast that heavy rainfall to continue, particularly over north Tamil Nadu, through the week.
The system off the Tamil Nadu coast brought overnight torrential rains in several parts of the State. It is expected to move across north T.N., Puducherry and south Andhra Pradesh coasts while maintaining its strength and showing almost no scope for further intensification.
Also Read: Rains LIVE | Updates on October 22, 2025
Chennai and its neighbouring districts are likely to receive heavy rainfall on Thursday (October 23, 2025), and a similar rain pattern may continue especially in north T.N. districts till October 28. The RMC has forecast scattered rainfall to continue over T.N. till October 28 interspersed with heavy spells in various districts.
Elaborating on the weather system losing its strength, B.Amudha, Head (Additional in-charge), RMC, said there are many interconnected and dynamic factors that can cause weakening of a weather system.
One of the cloud masses in the southern hemisphere that had influenced the weather systems in the Bay of Bengal and Arabian sea moved away, causing the cloud banding to diffuse. Moreover, the system travelled close to the coast rather than over the open seas, and its interaction with land areas limited the time available for further intensification, she said.
In contrast, the weather system in Arabian sea consolidated into a depression. The upper air circulation over south Andaman sea persists, contributing to the wet spell over the region.
Meanwhile, the northeast monsoon in its vigorous mode pounded most districts across the State. Periyakalapet in Puducherry recorded extremely heavy rainfall of 25 cm in the 24 hours ending 8:30 a.m. on Wednesday (October 22). While 23 places, including Puducherry, Villupuram and Cuddalore, reported very heavy rainfall, heavy rainfall lashed 102 places in other districts such as Chennai, Kallakurichi, Karur and Chengalpattu.
On Wednesday (October 22), various places, including Harur (7.3 cm), Dharmapuri (6 cm), Udhagamandalam, Karur and Kallakurichi (3 cm each) and Yercaud, Madurai, Salem and Tiruvannamalai (2 cm each), recorded moderate to heavy rainfall till 6 p.m.
Water release increased
With overnight downpour bringing heavy inflows, floodgates of three major reservoirs in Chembarambakkam, Red Hills and Poondi were opened wider to regulate the water level and prevent flood risk on Wednesday (October 22).
Following widespread rainfall, the 90 major water bodies in the State now have a storage of 87.7% of their total capacity of 224.34 thousand million cubic feet.
In Chennai region, with Chembarambakkam reservoir’s storage rising steadily to 2,872 millon cubic feet (mcft) against 3,645 mcft., the department increased water discharge from 100 cubic feet per second to 500 cusecs into Adyar River on Wednesday morning (October 22). The measure would enable balance of storage and accommodate heavy inflows, said an official of the Water Resources Department.
Similarly, the water release from reservoirs in Poondi and Red Hills were stepped up to 4,500 cusecs and 750 cusecs respectively to maintain water level two feet lower than full capacity.
Published – October 22, 2025 09:21 pm IST
