AirHint found the following cheapest one-way flights from Seattle (SEA) to San Jose (SJO) in December 2025 (see full year).
One-Way flights
| 10 Dec | Alaska Airlines | ||
| 08 Dec | Delta | ||
| 15 Dec | Frontier Airlines | ||
| 14 Dec | United | ||
| 24 Dec | Frontier Airlines | ||
| 22 Dec | United |
Also check the deals for return flights from Seattle to San Jose in December.
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