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

Return flights

18 Sep - 22 Sep	Spirit Airlines
30 Sep - 06 Oct	Spirit Airlines
01 Sep - 06 Sep	Spirit Airlines
02 Sep - 09 Sep	Spirit Airlines
18 Sep - 06 Oct	Spirit Airlines
18 Sep - 23 Sep	Spirit Airlines
10 Sep - 18 Sep	Spirit Airlines
07 Sep - 10 Sep	Spirit Airlines
05 Sep - 08 Sep	Spirit Airlines
30 Sep - 09 Oct	Spirit Airlines

Also check the deals for one-way flights from Philadelphia 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 Philadelphia to San Jose in September from $351

Return flights