AirHint found the following cheapest return flights from San Francisco (SFO) to Keflavik (KEF) in May 2026 (see full year).

Return flights

01 May - 08 May	Alaska Airlines
02 May - 09 May	jetBlue
24 May - 01 Jun	WestJet
12 May - 19 May	Aer Lingus
11 May - 18 May	Scandinavian Airlines
09 May - 16 May	Scandinavian Airlines
14 May - 21 May	Scandinavian Airlines
10 May - 17 May	Alaska Airlines
15 May - 22 May	WestJet
09 May - 23 May	Scandinavian Airlines
13 May - 20 May	jetBlue
26 May - 03 Jun	WestJet

Also check the deals for one-way flights from San Francisco to Keflavik in May.

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 San Francisco to Keflavik in May from 532€

Return flights