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

Return flights

26 Sep - 29 Sep	Ryanair
26 Sep - 01 Oct	Ryanair
26 Sep - 28 Sep	Ryanair
29 Sep - 04 Oct	Ryanair
24 Sep - 29 Sep	Vueling Airlines
25 Sep - 28 Sep	Norwegian Air Sweden AOC
19 Sep - 27 Sep	Aer Lingus
20 Sep - 28 Sep	TAP
24 Sep - 28 Sep	Ryanair
23 Sep - 18 Oct	Vueling Airlines
30 Sep - 03 Oct	Aer Lingus
18 Sep - 22 Sep	Volotea
13 Sep - 27 Sep	Air Europa
23 Sep - 30 Sep	Ryanair
22 Sep - 17 Oct	Ryanair
29 Sep - 04 Oct	airBaltic	direct

Also check the deals for one-way flights from Lisbon 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 Lisbon to Riga in September from $222

Return flights