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

Return flights

13 Sep - 04 Oct	Vueling Airlines
30 Sep - 04 Oct	Ryanair
17 Sep - 24 Sep	Ryanair
22 Sep - 28 Sep	Ryanair
30 Sep - 03 Oct	Ryanair
24 Sep - 01 Oct	easyJet
13 Sep - 17 Sep	Vueling Airlines
25 Sep - 28 Sep	Ryanair
10 Sep - 17 Sep	Ryanair
27 Sep - 01 Oct	Ryanair
23 Sep - 30 Sep	Vueling Airlines
20 Sep - 21 Sep	Ryanair
26 Sep - 30 Sep	Ryanair
18 Sep - 21 Sep	Ryanair
25 Sep - 30 Sep	Ryanair
27 Sep - 01 Oct	airBaltic	direct
13 Sep - 04 Oct	airBaltic	direct

Also check the deals for one-way flights from Porto to Riga 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 Porto to Riga in September from $219

Return flights