Cheapest return flights from Seattle to San Juan in December from 374€

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

Return flights

30 Dec - 11 Jan Frontier Airlines
12 Dec - 20 Dec Frontier Airlines
11 Dec - 17 Dec Frontier Airlines
19 Dec - 24 Dec Frontier Airlines
19 Dec - 22 Dec Frontier Airlines
11 Dec - 16 Dec Frontier Airlines
19 Dec - 25 Dec Frontier Airlines
24 Dec - 01 Jan Sun Country Airlines
24 Dec - 29 Dec Sun Country Airlines
24 Dec - 31 Dec Sun Country Airlines
25 Dec - 31 Dec Frontier Airlines
10 Dec - 17 Dec Aeromexico
28 Dec - 04 Jan Frontier Airlines
19 Dec - 02 Jan Frontier Airlines
27 Dec - 03 Jan Frontier Airlines
27 Dec - 10 Jan Delta
29 Dec - 04 Jan Delta

Also check the deals for one-way flights from Seattle to San Juan in December.

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