AirHint found the following cheapest one-way flights from Seattle (SEA) to Madrid (MAD) in December 2025 (see full year).
One-Way flights
| 31 Dec | Aer Lingus | ||
| 10 Dec | Air France | ||
| 30 Dec | Hawaiian Airlines | ||
| 11 Dec | United | ||
| 09 Dec | Iberia | ||
| 06 Dec | Iberia | ||
| 23 Dec | British Airways | ||
| 26 Dec | British Airways | ||
| 28 Dec | Iberia | ||
| 29 Dec | Iberia |
Also check the deals for return flights from Seattle to Madrid in December.
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