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

Return flights

26 Sep - 24 Oct	Condor
03 Sep - 10 Sep	United
09 Sep - 16 Sep	United
05 Sep - 12 Sep	United
11 Sep - 18 Sep	United
07 Sep - 14 Sep	United
17 Sep - 24 Sep	United
24 Sep - 01 Oct	Lufthansa
30 Sep - 07 Oct	Lufthansa
13 Sep - 20 Sep	United
19 Sep - 26 Sep	United
21 Sep - 28 Sep	United
01 Sep - 08 Sep	United
27 Sep - 04 Oct	Lufthansa

Also check the deals for one-way flights from San Juan to Frankfurt 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 Juan to Frankfurt in September from 600€

Return flights