Cheapest return flights from Seattle to London in September from $582

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

Return flights

26 Sep - 03 Oct Icelandair
01 Sep - 11 Sep Finnair
04 Sep - 18 Sep Scandinavian Airlines
13 Sep - 30 Sep Aer Lingus
01 Sep - 16 Sep Finnair
14 Sep - 28 Sep Air Canada
06 Sep - 12 Sep Scandinavian Airlines
01 Sep - 05 Sep Scandinavian Airlines
13 Sep - 30 Sep British Airways direct
03 Sep - 10 Sep Air Canada
04 Sep - 18 Sep British Airways direct
26 Sep - 03 Oct Air France direct

Also check the deals for one-way flights from Seattle to London in September.

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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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