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

Return flights

08 Sep - 16 Sep	United
09 Sep - 16 Sep	United
17 Sep - 21 Sep	Southwest Airlines
01 Sep - 05 Sep	United
18 Sep - 21 Sep	Southwest Airlines
14 Sep - 21 Sep	Copa
28 Sep - 05 Oct	Copa
02 Sep - 05 Sep	Southwest Airlines
19 Sep - 21 Sep	Copa

Also check the deals for one-way flights from Denver 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 Denver to San Jose in September from 202€

Return flights