Cheapest return SEA–SYD flights, December

AirHint found the following cheapest return flights from Seattle (SEA) to Sydney (SYD) in December 2026 (see full year).

Return flights

11 Dec - 29 Dec Air Canada
20 Dec - 30 Dec Alaska Airlines
14 Dec - 02 Jan Air Canada

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

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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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