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

Return flights

18 Aug - 27 Aug	jetBlue
22 Aug - 31 Aug	Aer Lingus
11 Aug - 20 Aug	Spirit Airlines
11 Aug - 20 Aug	British Airways	direct
18 Aug - 27 Aug	British Airways	direct
27 Aug - 06 Sep	TAP
09 Aug - 19 Aug	TAP
08 Aug - 19 Aug	TAP
09 Aug - 19 Aug	Iberia	direct
28 Aug - 01 Sep	TAP
01 Aug - 09 Aug	TAP
10 Aug - 19 Aug	TAP
14 Aug - 01 Sep	TAP
26 Aug - 02 Sep	United
31 Aug - 07 Sep	United
28 Aug - 04 Sep	United
27 Aug - 06 Sep	Iberia	direct

Also check the deals for one-way flights from Philadelphia 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 Philadelphia to Lisbon in August from 577€

Return flights