AirHint found the following cheapest return flights from Portland (PDX) to Keflavik (KEF) in August 2025 (see full year).

Return flights

18 Aug - 27 Aug	Icelandair	direct
13 Aug - 11 Sep	Air Canada
21 Aug - 29 Aug	Icelandair	direct
29 Aug - 11 Sep	Icelandair	direct
25 Aug - 07 Sep	Air Canada
25 Aug - 07 Sep	Icelandair	direct
02 Aug - 09 Aug	Lufthansa
04 Aug - 06 Aug	Icelandair	direct
13 Aug - 11 Sep	Icelandair	direct

Also check the deals for one-way flights from Portland to Keflavik 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 Portland to Keflavik in August from $462

Return flights