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	TAP
26 Aug - 02 Sep	TAP
18 Aug - 30 Aug	TAP
19 Aug - 27 Aug	jetBlue
18 Aug - 26 Aug	Aer Lingus
29 Aug - 02 Sep	Aer Lingus
31 Aug - 08 Sep	TAP
07 Aug - 12 Aug	TAP
18 Aug - 26 Aug	British Airways	direct
11 Aug - 20 Aug	Finnair	direct
18 Aug - 27 Aug	American Airlines	direct
19 Aug - 28 Aug	American Airlines	direct
19 Aug - 27 Aug	American Airlines	direct
27 Aug - 01 Sep	jetBlue
14 Aug - 01 Sep	TAP
22 Aug - 01 Sep	Aer Lingus
26 Aug - 02 Sep	American Airlines	direct
31 Aug - 08 Sep	British Airways	direct
14 Aug - 01 Sep	American Airlines	direct
27 Aug - 03 Sep	United

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 $666

Return flights