AirHint found the following cheapest return flights from Portland (PDX) to London (STN) in December 2025 (see full year).

Return flights

05 Dec - 12 Dec	Hawaiian Airlines
03 Dec - 07 Dec	Alaska Airlines
05 Dec - 07 Dec	Hawaiian Airlines
21 Dec - 10 Jan	Hawaiian Airlines
30 Dec - 09 Jan	Hawaiian Airlines
02 Dec - 06 Dec	Icelandair
21 Dec - 05 Jan	Hawaiian Airlines
22 Dec - 01 Jan	Icelandair
23 Dec - 29 Dec	Hawaiian Airlines
22 Dec - 02 Jan	Hawaiian Airlines
29 Dec - 04 Jan	Icelandair

Also check the deals for one-way flights from Portland to London in December.

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 London in December from 724€

Return flights