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

Return flights

02 Dec - 06 Dec	Volaris El Salvador
08 Dec - 16 Dec	Avianca	direct
11 Dec - 18 Dec	Avianca	direct
09 Dec - 15 Dec	Avianca	direct
02 Dec - 06 Dec	Avianca	direct
02 Dec - 15 Dec	Avianca	direct
03 Dec - 07 Dec	Copa
13 Dec - 21 Dec	Frontier Airlines
21 Dec - 29 Dec	Volaris El Salvador
07 Dec - 09 Dec	Avianca
30 Dec - 06 Jan	Avianca
29 Dec - 02 Jan	Avianca
24 Dec - 12 Jan	Volaris El Salvador
30 Dec - 03 Jan	Avianca
22 Dec - 05 Jan	American Airlines
29 Dec - 06 Jan	Avianca
29 Dec - 03 Jan	Avianca
15 Dec - 02 Jan	Avianca
27 Dec - 03 Jan	Volaris El Salvador
26 Dec - 03 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 $234

Return flights