The highly anticipated Northeast monsoon, responsible for a significant portion of Tamil Nadu’s annual rainfall, made an early entrance this year, arriving on Thursday, October 16, 2025. This is notably ahead of its typical onset around October 20.
Chennai’s Regional Meteorological Centre (RMC) confirmed the dual meteorological event: the Southwest monsoon has officially withdrawn from the nation, while the Northeast monsoon has simultaneously begun its rainfall over the southern peninsular areas, specifically Tamil Nadu, Puducherry, and Karaikal.
Experts at the RMC pointed to an upper air cyclonic circulation hovering over the Comorin region, which has already delivered widespread rain across much of the state, coupled with the shift to easterly winds, as the primary factors signaling the monsoon’s arrival.
Interestingly, Tamil Nadu experienced a similar early start to the Northeast monsoon last year, arriving on October 15. That season concluded favorably, delivering a remarkable 33% excess rainfall.
The initial burst of this year’s monsoon has already unleashed significant rainfall. Over the 24-hour period concluding at 8:30 a.m. on Thursday, locations like Kayalpattinam and Thoothukudi recorded a substantial 15 cm of rain each, with Thiruchendur close behind at 13 cm. Other regions such as Ranipet, Tirunelveli, and Mayiladuthurai also experienced heavy downpours, while Chennai and its surrounding areas saw moderate showers.
In response to the intensifying weather, the RMC has issued an orange alert for Theni, Tenkasi, Tirunelveli, and Ramanathapuram districts, signaling the potential for isolated instances of very heavy rainfall throughout Thursday. Furthermore, heavy rain is predicted for an additional 22 districts, encompassing major cities like Chennai, Madurai, and Erode.
Concurrently, the Water Resources Department in Tiruvallur district has increased the water release from the Poondi reservoir to 4,500 cubic feet per second. This measure comes as heavy inflows cause the water level in this crucial drinking water source for Chennai to rise significantly. Authorities explained that some of the released water is being redirected to the Cholavaram tank for storage, while the remainder flows into downstream check dams along the Kosasthalaiyar river.