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

Return flights

03 Sep - 31 Oct	Avianca
29 Sep - 08 Oct	Avianca
29 Sep - 06 Oct	Avianca
27 Sep - 10 Oct	Air Transat
27 Sep - 13 Oct	Air Transat
23 Sep - 30 Sep	Copa
07 Sep - 10 Sep	Avianca
08 Sep - 23 Sep	Avianca
24 Sep - 01 Oct	Avianca
14 Sep - 21 Sep	Avianca
17 Sep - 24 Sep	Avianca
01 Sep - 05 Sep	Avianca
14 Sep - 24 Sep	Avianca
10 Sep - 19 Sep	Avianca
02 Sep - 09 Sep	Porter Airlines (Canada) Ltd
08 Sep - 15 Sep	Avianca
27 Sep - 12 Oct	Porter Airlines (Canada) Ltd
30 Sep - 08 Oct	Porter Airlines (Canada) Ltd
28 Sep - 05 Oct	Avianca
28 Sep - 11 Oct	Avianca

Also check the deals for one-way flights from Montreal to San Jose 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 San Jose in September from $324

Return flights