AirHint found the following cheapest return flights from Raleigh-durham (RDU) to Lisbon (LIS) in September 2025 (see full year).

Return flights

08 Sep - 10 Sep	Spirit Airlines
22 Sep - 26 Sep	Spirit Airlines
23 Sep - 30 Sep	United
30 Sep - 07 Oct	United
17 Sep - 27 Sep	Turkish Airlines
09 Sep - 16 Sep	United
03 Sep - 10 Sep	United
25 Sep - 02 Oct	United
01 Sep - 08 Sep	United
11 Sep - 18 Sep	United
15 Sep - 22 Sep	United
13 Sep - 20 Sep	United

Also check the deals for one-way flights from Raleigh-durham to Lisbon in September.

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 Raleigh-durham to Lisbon in September from $679

Return flights