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

Return flights

01 Dec - 09 Dec	Avianca	direct
06 Dec - 09 Dec	Avianca	direct
09 Dec - 15 Dec	Avianca	direct
09 Dec - 13 Dec	Avianca	direct
08 Dec - 13 Dec	Avianca	direct
02 Dec - 11 Dec	Avianca	direct
13 Dec - 15 Dec	Frontier Airlines
11 Dec - 23 Dec	United
10 Dec - 16 Dec	Copa
12 Dec - 16 Dec	Copa
30 Dec - 07 Jan	Avianca
30 Dec - 06 Jan	Frontier Airlines
29 Dec - 06 Jan	Avianca
25 Dec - 12 Jan	Volaris El Salvador
24 Dec - 12 Jan	Avianca
27 Dec - 06 Jan	Volaris El Salvador
30 Dec - 04 Jan	Volaris El Salvador
28 Dec - 04 Jan	Volaris El Salvador
25 Dec - 04 Jan	Volaris El Salvador
30 Dec - 03 Jan	Volaris El Salvador

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 $234

Return flights