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

Return flights

12 Aug - 26 Aug	Finnair
05 Aug - 29 Aug	United
12 Aug - 22 Aug	Air Canada
05 Aug - 29 Aug	British Airways	direct
09 Aug - 23 Aug	Air Canada
09 Aug - 23 Aug	British Airways	direct
12 Aug - 26 Aug	British Airways	direct
14 Aug - 05 Sep	Air Canada
12 Aug - 22 Aug	British Airways	direct
13 Aug - 05 Sep	Virgin Atlantic	direct
14 Aug - 05 Sep	Virgin Atlantic	direct

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 540€

Return flights