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

Return flights

27 Aug - 24 Sep	Ryanair
26 Aug - 09 Sep	Ryanair
23 Aug - 27 Aug	Norwegian Air Sweden AOC
24 Aug - 31 Aug	Ryanair
26 Aug - 30 Aug	Norwegian Air Sweden AOC
21 Aug - 28 Aug	Ryanair
27 Aug - 30 Aug	Ryanair
20 Aug - 23 Aug	Ryanair
19 Aug - 26 Aug	Lufthansa
23 Aug - 30 Aug	Norwegian Air Sweden AOC
23 Aug - 31 Aug	Ryanair
22 Aug - 28 Aug	Ryanair
27 Aug - 24 Sep	airBaltic	direct
26 Aug - 23 Sep	TAP

Also check the deals for one-way flights from Riga to Porto in August.

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 Porto in August from 247€

Return flights