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

Return flights

08 Dec - 12 Dec	Delta
02 Dec - 11 Dec	Delta
08 Dec - 12 Dec	United	direct
04 Dec - 08 Dec	Frontier Airlines
02 Dec - 06 Dec	United	direct
04 Dec - 06 Dec	Delta
31 Dec - 09 Jan	Delta
04 Dec - 06 Dec	United	direct
03 Dec - 09 Dec	United	direct
12 Dec - 19 Dec	Frontier Airlines
17 Dec - 23 Dec	United	direct
28 Dec - 09 Jan	United	direct
28 Dec - 04 Jan	Frontier Airlines	direct
27 Dec - 04 Jan	Frontier Airlines	direct
24 Dec - 04 Jan	Frontier Airlines
24 Dec - 01 Jan	Frontier Airlines
24 Dec - 09 Jan	United
23 Dec - 06 Jan	United	direct
31 Dec - 04 Jan	Delta

Also check the deals for one-way flights from Washington to San Juan 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 Juan in December from 184€

Return flights