AirHint found the following cheapest return flights from Boston (BOS) to Lisbon (LIS) in August 2025 (see full year).

Return flights

18 Aug - 27 Aug	Air Canada
19 Aug - 28 Aug	Air Canada
18 Aug - 26 Aug	Iberia
20 Aug - 26 Aug	Air Canada
20 Aug - 27 Aug	Air Canada
21 Aug - 04 Sep	Air Canada
21 Aug - 26 Aug	Air Canada
03 Aug - 29 Sep	Iberia
20 Aug - 29 Aug	Air Canada
10 Aug - 26 Aug	Air Canada
31 Aug - 08 Sep	Air Canada
17 Aug - 25 Aug	SWISS
19 Aug - 28 Aug	TAP	direct
26 Aug - 03 Sep	TAP	direct
27 Aug - 03 Sep	TAP	direct
28 Aug - 06 Sep	TAP
28 Aug - 01 Sep	TAP	direct
29 Aug - 08 Sep	Icelandair
30 Aug - 08 Sep	SWISS
30 Aug - 13 Sep	SWISS

Also check the deals for one-way flights from Boston to Lisbon 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 Boston to Lisbon in August from $453

Return flights