The cheapest Luxembourg to San Juan return flight on the radar right now is €804, flying with British Airways via one or more connections. It covers departures in April 2027, and every dated link below opens that exact LUX–SJU search on Skyscanner. The price we usually record on this route is €785. Across 35 recorded checks it has ranged between €715 and €847. Our sampling points to April 2027 as the cheapest month to fly Luxembourg to San Juan.
Prices are re-checked against Skyscanner automatically, and every one shows when it was last confirmed, so nothing here is older than it looks. Not flying from Luxembourg? We track 53 other departure cities for San Juan, listed at the foot of this page.
Prices like this tend to vanish fast. If it has gone when you look, try the days either side of the dates above, since Luxembourg to San Juan is often still worth booking within a day or two of the fare we found.