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

Return flights

03 Dec - 18 Dec	Delta
11 Dec - 23 Dec	Delta
31 Dec - 07 Jan	Virgin Atlantic
02 Dec - 06 Dec	Icelandair
05 Dec - 13 Dec	KLM
08 Dec - 15 Dec	Icelandair
30 Dec - 06 Jan	KLM
16 Dec - 10 Jan	KLM
23 Dec - 17 Jan	Hawaiian Airlines
23 Dec - 29 Dec	KLM
14 Dec - 28 Dec	Delta
13 Dec - 04 Jan	Hawaiian Airlines
18 Dec - 10 Jan	Hawaiian Airlines
19 Dec - 10 Jan	United
11 Dec - 03 Jan	Frontier Airlines
12 Dec - 03 Jan	Alaska Airlines
21 Dec - 05 Jan	Hawaiian Airlines
22 Dec - 30 Dec	Delta
22 Dec - 31 Dec	United
06 Dec - 13 Dec	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 513€

Return flights