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

Return flights

26 Aug - 31 Aug	Icelandair
13 Aug - 03 Sep	Icelandair
21 Aug - 26 Aug	Icelandair
22 Aug - 27 Aug	Icelandair
23 Aug - 30 Aug	Icelandair
24 Aug - 29 Aug	Icelandair
23 Aug - 29 Aug	Icelandair
26 Aug - 30 Aug	Icelandair
24 Aug - 30 Aug	Icelandair
25 Aug - 30 Aug	Icelandair
30 Aug - 04 Sep	Icelandair
13 Aug - 18 Aug	Icelandair
29 Aug - 03 Sep	Icelandair

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

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 Seattle to London in August from $771

Return flights