AirHint found the following cheapest return flights from Frankfurt (FRA) to San Jose (SJO) in September 2025 (see full year).

Return flights

18 Sep - 04 Oct	Air France
12 Sep - 01 Oct	Air France
11 Sep - 24 Sep	Air France
24 Sep - 03 Oct	SWISS
09 Sep - 24 Sep	Air France
15 Sep - 05 Oct	Air France
22 Sep - 03 Oct	KLM
25 Sep - 04 Oct	KLM
24 Sep - 02 Oct	KLM
16 Sep - 02 Oct	Air France
17 Sep - 01 Oct	Air Canada
15 Sep - 22 Sep	Air France
11 Sep - 23 Sep	Air France
10 Sep - 22 Sep	Air France
16 Sep - 30 Sep	United
16 Sep - 23 Sep	United
21 Sep - 25 Sep	United
20 Sep - 27 Sep	United
18 Sep - 30 Sep	United
29 Sep - 07 Oct	United

Also check the deals for one-way flights from Frankfurt to San Jose 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 Frankfurt to San Jose in September from $599

Return flights