AirHint found the following cheapest return flights from San Francisco (SFO) to Sydney (SYD) in September 2025 (see full year).

Return flights

10 Sep - 18 Sep	Air Canada
14 Sep - 21 Sep	Fiji Airways
23 Sep - 01 Oct	China Southern
25 Sep - 12 Oct	Frontier Airlines
10 Sep - 24 Sep	Air Canada
14 Sep - 23 Sep	Air Canada
16 Sep - 23 Sep	Air Canada
25 Sep - 29 Sep	Frontier Airlines
22 Sep - 29 Sep	Frontier Airlines
19 Sep - 28 Sep	Asiana Airlines
12 Sep - 28 Sep	Asiana Airlines
13 Sep - 20 Sep	Asiana Airlines
26 Sep - 05 Oct	Frontier Airlines
21 Sep - 12 Oct	United	direct
25 Sep - 12 Oct	United	direct
21 Sep - 01 Oct	United	direct

Also check the deals for one-way flights from San Francisco to Sydney 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 San Francisco to Sydney in September from 805€

Return flights