AirHint found the following cheapest return flights from Montreal (YUL) to Chicago (ORD) in August 2025 (see full year).

Return flights

15 Aug - 22 Aug	Air Canada
19 Aug - 26 Aug	Air Canada	direct
31 Aug - 02 Sep	United	direct
30 Aug - 06 Sep	Air Canada	direct
27 Aug - 03 Sep	Air Canada	direct
29 Aug - 05 Sep	Air Canada	direct
31 Aug - 07 Sep	Air Canada	direct
22 Aug - 02 Sep	Delta
20 Aug - 27 Aug	Air Canada	direct
23 Aug - 30 Aug	Air Canada	direct
22 Aug - 02 Sep	United	direct
12 Aug - 19 Aug	Delta
12 Aug - 23 Aug	Delta
15 Aug - 18 Aug	Delta
01 Aug - 08 Aug	Delta
05 Aug - 08 Aug	Delta
16 Aug - 23 Aug	Delta
08 Aug - 05 Sep	Delta
08 Aug - 05 Sep	Air Canada	direct
31 Aug - 01 Sep	United	direct

Also check the deals for one-way flights from Montreal to Chicago 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 Montreal to Chicago in August from 164€

Return flights