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

Return flights

07 Dec - 12 Dec	Southwest Airlines
14 Dec - 20 Dec	Southwest Airlines
30 Dec - 07 Jan	Frontier Airlines
22 Dec - 10 Jan	Frontier Airlines
27 Dec - 10 Jan	Frontier Airlines
31 Dec - 06 Jan	United
26 Dec - 10 Jan	Frontier Airlines
24 Dec - 30 Dec	United
29 Dec - 06 Jan	United	direct
28 Dec - 06 Jan	Copa
28 Dec - 06 Jan	United	direct
20 Dec - 25 Dec	Frontier Airlines

Also check the deals for one-way flights from Denver to San Jose in December.

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 December from 305€

Return flights