AirHint found the following cheapest one-way flights from St. Louis (STL) to San Juan (SJU) in December 2025 (see full year).
One-Way flights
| 13 Dec | Frontier Airlines | ||
| 17 Dec | Frontier Airlines | ||
| 21 Dec | Spirit Airlines | ||
| 18 Dec | Spirit Airlines | ||
| 27 Dec | Southern Airways Express | ||
| 13 Dec | Southwest Airlines | direct | |
| 27 Dec | Southwest Airlines | direct |
Also check the deals for return flights from St. Louis 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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