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

Return flights

18 Sep - 30 Sep	Air Canada
23 Sep - 10 Oct	Air Canada
23 Sep - 09 Oct	Air Canada
30 Sep - 05 Oct	Air India
24 Sep - 29 Oct	Air Canada
21 Sep - 08 Oct	Air India
19 Sep - 03 Oct	Air India
18 Sep - 03 Oct	Air India
21 Sep - 28 Sep	Air India
25 Sep - 17 Oct	Air India
18 Sep - 25 Sep	Air India
25 Sep - 12 Oct	Air India
24 Sep - 02 Oct	Air India

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.

Book a cheap hotel in Kathmandu

Cheap car rent in Kathmandu

Cheapest return flights from Washington to Kathmandu in September from $1331

Return flights