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

Return flights

22 Sep - 01 Oct	Air Transat	direct
29 Sep - 14 Oct	Air France
21 Sep - 05 Oct	Air France
24 Sep - 01 Oct	Air France
25 Sep - 02 Oct	Air France
27 Sep - 04 Oct	Air France
28 Sep - 05 Oct	Air France
29 Sep - 06 Oct	Air France
30 Sep - 07 Oct	Air France
26 Sep - 03 Oct	Air France
20 Sep - 27 Sep	Air France
21 Sep - 28 Sep	Air France
23 Sep - 30 Sep	Air France
22 Sep - 26 Sep	FrenchBee
22 Sep - 29 Sep	Delta
22 Sep - 29 Sep	Air Transat	direct
19 Sep - 24 Sep	TAP	direct
19 Sep - 26 Sep	FrenchBee
25 Sep - 30 Sep	Azores Airlines
19 Sep - 25 Sep	FrenchBee

Also check the deals for one-way flights from Montreal to Lisbon 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 Montreal to Lisbon in September from $493

Return flights