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

Return flights

09 Dec - 16 Dec	United
09 Dec - 15 Dec	United
07 Dec - 13 Dec	United
11 Dec - 16 Dec	Frontier Airlines
11 Dec - 15 Dec	Frontier Airlines
10 Dec - 16 Dec	United
03 Dec - 07 Dec	Copa
15 Dec - 22 Dec	Frontier Airlines
06 Dec - 22 Dec	Copa
12 Dec - 15 Dec	Frontier Airlines
25 Dec - 12 Jan	Frontier Airlines
24 Dec - 12 Jan	Frontier Airlines
25 Dec - 13 Jan	Frontier Airlines
19 Dec - 10 Jan	Frontier Airlines
28 Dec - 02 Jan	Frontier Airlines
27 Dec - 01 Jan	Frontier Airlines
28 Dec - 01 Jan	Frontier Airlines
25 Dec - 03 Jan	Frontier Airlines
30 Dec - 03 Jan	Copa
20 Dec - 04 Jan	Frontier Airlines

Also check the deals for one-way flights from Washington 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 Washington to San Jose in December from 226€

Return flights