AirHint found the following cheapest return flights from Riga (RIX) to Keflavik (KEF) in September 2025 (see full year).

Return flights

30 Sep - 04 Oct	Ryanair
28 Sep - 02 Oct	Ryanair
26 Sep - 04 Oct	airBaltic
23 Sep - 25 Sep	Ryanair
25 Sep - 28 Sep	Ryanair
10 Sep - 29 Sep	Ryanair
26 Sep - 04 Oct	airBaltic	direct
25 Sep - 27 Sep	Ryanair
26 Sep - 29 Sep	airBaltic
05 Sep - 06 Sep	Finnair
08 Sep - 15 Sep	airBaltic
04 Sep - 05 Sep	Finnair
04 Sep - 04 Sep	Finnair
10 Sep - 29 Sep	Icelandair	direct
28 Sep - 02 Oct	airBaltic	direct

Also check the deals for one-way flights from Riga to Keflavik in September.

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 Riga to Keflavik in September from $225

Return flights