Ditto on Pilot Charts: http://msi.nga.mil/NGAPortal/MSI.por...ubConstant=APC
Lots of land effect in play when near shore. The upper air winds are not really what you need to look at. Pressure systems that effect sailing are in surface forecasts. Use this NOAA link: Radiofax Charts - Boston
to compare upper/lower level winds. In the summer, the Atlantic is usually dominated by high pressure. Getting toward fall, the high weakens and northern lows become more predominant. They can raise hell with the opposing Gulf Stream.
Jimmy Cornell's World Cruising Routes has a great section on weather patterns, trade winds, etc.
Hope these help... and welcome. There are lot of helpful, knowledgeable people on this board.