India in September: Weather, Where to Go, and What to Avoid

• Golden Triangle and Rajasthan — still warm and humid early in the month, cooling and drying as the monsoon retreats.
• Kerala and Goa — drying out through the month, though rain is still possible.
• Rishikesh — the Ganges' rafting season typically resumes toward the end of the month.
• Ladakh — its main season is winding down as fewer travellers use the high passes.

September rewards flexibility: it can be an excellent, less crowded shoulder-season month, but the exact point the monsoon clears varies by year and region, so build a little slack into an early-month itinerary.

• Ganesh Chaturthi — widely celebrated, especially in Maharashtra (date varies with the lunar calendar, usually August or September).
• Onam — in some years falls in September rather than August (date varies).

• Booking a rigid early-September itinerary assuming the monsoon has fully cleared — it's still retreating in many regions.
• Assuming Rishikesh rafting is running before you check — the restart depends on river conditions that year.