AirHint found the following cheapest return flights from Portland (PDX) to Lisbon (LIS) in October 2025 (see full year).

Return flights

15 Oct - 03 Nov	Delta
29 Oct - 17 Nov	Delta
20 Oct - 30 Oct	KLM
13 Oct - 31 Oct	Delta
31 Oct - 07 Nov	Delta
13 Oct - 30 Oct	Delta
04 Oct - 23 Oct	Delta
05 Oct - 23 Oct	British Airways
19 Oct - 08 Nov	KLM
03 Oct - 02 Nov	Air France
03 Oct - 24 Oct	Air France
11 Oct - 01 Nov	WestJet
10 Oct - 01 Nov	Frontier Airlines
08 Oct - 13 Oct	Hawaiian Airlines
09 Oct - 18 Oct	Frontier Airlines
03 Oct - 06 Oct	Alaska Airlines

Also check the deals for one-way flights from Portland to Lisbon in October.

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 Portland to Lisbon in October from 484€

Return flights