Kolkata Weather in September

Kolkata's tropical wet-and-dry climate is dominated by the Bay of Bengal monsoon, the Hooghly River corridor, and the vast deltaic floodplain of the Ganges. The city experiences extreme humidity from May through October, with the river and surrounding wetlands amplifying moisture levels, while winter months bring dry northwesterly winds and brief cool spells. The dense urban core generates a pronounced heat island effect, but the Hooghly riverfront, the East Kolkata Wetlands, and the Maidan parkland create significant cooling corridors that shape neighborhood-level weather.

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