AirHint found the following cheapest return flights from Washington (IAD) to Kathmandu (KTM) in September 2025 (see full year).

Return flights

13 Sep - 28 Sep	Saudia
17 Sep - 26 Sep	Etihad Airways
03 Sep - 10 Sep	Etihad Airways
02 Sep - 09 Sep	Etihad Airways
14 Sep - 05 Oct	Etihad Airways
05 Sep - 13 Sep	Etihad Airways
17 Sep - 24 Oct	SWISS
28 Sep - 13 Oct	SWISS
24 Sep - 11 Oct	Etihad Airways
10 Sep - 28 Oct	Etihad Airways
24 Sep - 27 Oct	SWISS
25 Sep - 27 Oct	SWISS
24 Sep - 26 Oct	SWISS
26 Sep - 29 Oct	SWISS
26 Sep - 30 Oct	SWISS
07 Sep - 28 Sep	Emirates

Also check the deals for one-way flights from Washington to Kathmandu in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Washington to Kathmandu in September from $825

Return flights