Cheapest one-way flights from Seattle to San Juan in December from $213

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

One-Way flights

02 Dec Alaska Airlines
28 Dec Frontier Airlines
03 Dec Alaska Airlines
22 Dec Frontier Airlines
16 Dec United
19 Dec Sun Country Airlines
21 Dec Frontier Airlines
20 Dec Sun Country Airlines
23 Dec Sun Country Airlines
18 Dec Sun Country Airlines

Also check the deals for return flights from Seattle to San Juan in December.

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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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