AirHint found the following cheapest return flights from Washington (IAD) to Calgary (YYC) in September 2025 (see full year).

Return flights

29 Sep - 03 Oct	WestJet	direct
26 Sep - 03 Oct	WestJet	direct
22 Sep - 29 Sep	WestJet	direct
12 Sep - 19 Sep	WestJet	direct
01 Sep - 22 Sep	WestJet	direct
08 Sep - 12 Sep	WestJet	direct
12 Sep - 16 Sep	WestJet
12 Sep - 17 Sep	WestJet
12 Sep - 18 Sep	WestJet
24 Sep - 29 Sep	Frontier Airlines
01 Sep - 08 Sep	WestJet
21 Sep - 29 Sep	Frontier Airlines

Also check the deals for one-way flights from Washington to Calgary 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 Washington to Calgary in September from $168

Return flights