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

Return flights

12 May - 20 May	Scandinavian Airlines
05 May - 13 May	Scandinavian Airlines
26 May - 02 Jun	WestJet
10 May - 18 May	Scandinavian Airlines
24 May - 01 Jun	WestJet
03 May - 11 May	Scandinavian Airlines
20 May - 28 May	WestJet
01 May - 09 May	Scandinavian Airlines
11 May - 19 May	Scandinavian Airlines
25 May - 02 Jun	WestJet
22 May - 30 May	WestJet
09 May - 17 May	Scandinavian Airlines
31 May - 08 Jun	WestJet
27 May - 04 Jun	WestJet
14 May - 24 May	Scandinavian Airlines
29 May - 06 Jun	WestJet
26 May - 03 Jun	jetBlue
28 May - 05 Jun	jetBlue
30 May - 07 Jun	jetBlue

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.

Book a cheap hotel in Keflavik

Cheap car rent in Keflavik

Cheapest return flights from San Francisco to Keflavik in May from $645

Return flights