Flew STT-BOS on Thu, 1/24. Plane was maybe 2/3's full. Pilot announced with full fuel we would be too heavy for Runway 10 (the default arrival and deaprture runway @ STT into the prevailing Easterly Tradewinds) and we would be taking off on Runway 28. The departure for that runway is over the Caribbean whereas Runway 10 departure requires a steep climb over the island hills/mountain. No need to stop @ SJU to refuel! Nice!