AirHint found the following cheapest return flights from Washington (IAD) to London (LHR) in September 2026 (see full year).

Return flights

17 Sep - 20 Sep	Scandinavian Airlines
06 Sep - 16 Sep	Scandinavian Airlines
17 Sep - 21 Sep	Scandinavian Airlines
08 Sep - 14 Sep	Air Canada
25 Sep - 10 Oct	Scandinavian Airlines
06 Sep - 16 Sep	Finnair	direct
08 Sep - 14 Sep	American Airlines	direct
17 Sep - 21 Sep	British Airways	direct
17 Sep - 20 Sep	American Airlines	direct

Also check the deals for one-way flights from Washington to London 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 London in September from $495

Return flights