AirHint found the following cheapest return flights from Washington (IAD) to Sydney (SYD) in December 2025 (see full year).

Return flights

07 Dec - 13 Dec	Delta
06 Dec - 13 Dec	Delta
05 Dec - 12 Dec	Delta
04 Dec - 11 Dec	Hawaiian Airlines
08 Dec - 15 Dec	Turkish Airlines
04 Dec - 26 Dec	Turkish Airlines
27 Dec - 19 Jan	IndiGo
05 Dec - 19 Dec	United
05 Dec - 18 Dec	United
23 Dec - 28 Dec	Air Canada
27 Dec - 10 Jan	Frontier Airlines
25 Dec - 14 Jan	Air Canada
26 Dec - 11 Jan	Frontier Airlines
17 Dec - 05 Jan	Frontier Airlines
26 Dec - 14 Jan	Turkish Airlines
17 Dec - 03 Jan	Frontier Airlines
19 Dec - 03 Jan	Frontier Airlines
20 Dec - 03 Jan	Frontier Airlines
23 Dec - 01 Jan	Frontier Airlines
18 Dec - 30 Dec	Hawaiian Airlines

Also check the deals for one-way flights from Washington to Sydney 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 Washington to Sydney in December from 736€

Return flights