AirHint found the following cheapest return flights from Calgary (YYC) to Seattle (SEA) in December 2025 (see full year).

Return flights

14 Dec - 27 Dec	WestJet
15 Dec - 15 Dec	Air Canada
16 Dec - 16 Dec	Air Canada
31 Dec - 03 Jan	WestJet
25 Dec - 30 Dec	WestJet
30 Dec - 01 Jan	WestJet
17 Dec - 24 Dec	Delta
26 Dec - 30 Dec	Flair Airlines
14 Dec - 27 Dec	WestJet	direct
31 Dec - 04 Jan	WestJet
29 Dec - 31 Dec	WestJet
18 Dec - 21 Dec	Delta
27 Dec - 30 Dec	Flair Airlines
31 Dec - 03 Jan	WestJet	direct
30 Dec - 01 Jan	Alaska Airlines	direct
31 Dec - 04 Jan	WestJet	direct

Also check the deals for one-way flights from Calgary to Seattle in December.

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 Calgary to Seattle in December from $390

Return flights