The southwest monsoon is on the verge of completing its withdrawal from the country very soon. Conditions are also becoming favourable for the onset of the northeast monsoon over the southeast peninsula to begin with. The entire coast of Tamil Nadu and adjoining south coastal Andhra Pradesh will be susceptible to heavy rains during this week. There is a likelihood of a strong weather system moving from east to west in the lower latitudes between 5°–10°N, across the Palk Strait, Gulf of Mannar, and Comorin area between October 16 and 18. It is a little early to confirm due to the limited precision of model forecasts beyond four days, yet the extreme southern parts of India — including the coastline of Tamil Nadu and pockets of Andhra Pradesh — need to be under close watch around the weekend.
October is the second rainiest month for Chennai after November. Nearly 300 mm of rainfall, and sometimes even more, is recorded over the capital city and its suburbs, as seen last year. The first half of the month remains under the southwest monsoon regime. So far, Chennai has recorded 52.2 mm of rainfall at Meenambakkam and 35.1 mm at Nungambakkam between October 1 and 13, 2025. The likely onset of the northeast monsoon anytime soon is expected to bring heavy showers towards the end of this week.
Chennai is likely to experience light rainfall today and tomorrow. The intensity will increase over the next two days with moderate showers expected. The scale and spread of rainfall will increase significantly on October 17 and partially on October 18, 2025. As the weather system moves to the southeast Arabian Sea and Lakshadweep region on October 19 and further toward the south-central Arabian Sea, weather conditions will ease along the Tamil Nadu and Andhra Pradesh coasts. By then, under the influence of the northeast monsoon, seasonal showers will become a regular feature along the coastline and even over the interior parts of Tamil Nadu.
