Chennai Weather in September

Chennai's tropical wet-and-dry climate is defined by its long Bay of Bengal coastline, which delivers the northeast monsoon from October to December — the city's primary rainy season, unusual for an Indian metro. The flat coastal plain offers little topographic relief, so microclimates are driven primarily by proximity to the sea, river corridors along the Adyar and Cooum, and dramatic variation in building density and green cover. Summer temperatures routinely exceed 40°C inland while coastal neighborhoods benefit from steady onshore sea breezes that moderate heat by 3–5°C.

Excellent shoulder season — warm with fewer tourists in many destinations.