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

Return flights

19 May - 26 May	jetBlue
18 May - 25 May	KLM
20 May - 27 May	jetBlue
30 May - 06 Jun	WestJet
23 May - 30 May	jetBlue
04 May - 08 May	Scandinavian Airlines
21 May - 28 May	Aer Lingus
17 May - 24 May	Scandinavian Airlines
29 May - 05 Jun	jetBlue
26 May - 02 Jun	WestJet
27 May - 03 Jun	jetBlue
28 May - 04 Jun	WestJet
22 May - 29 May	jetBlue
31 May - 07 Jun	WestJet
25 May - 05 Jun	WestJet
08 May - 12 May	Alaska Airlines

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 587€

Return flights