I became aware of the CBI Wind website while sailing in college. It was a great resource for figuring out the latest wind conditions on the Charles River. The site is maintained by Eric Wile who is an MIT alumnus who works in the Lincoln lab. He also wrote a program that solves those annoying Sudoku puzzles.
The wind on the Charles is tricky to say the least, although there was a definite advantage when sailing home regattas on the river.
The most consistent wind direction was a westerly (coming down the river basin) and the most shifty was a southerly (over Boston's Back Bay). There would also be a big hole extending part of the way across the river in a northerly caused by MIT's Green Building.
An interesting side note - the Google Map satellite photo of the Charles shows the BU team on the river during a practice:
And also the storm drain outlet that is underneath BU's rotation dock:
The Charles River is actually remarkably clean, despite the horror stories you may have heard about it. The Charles River Watershed Association checks the water quality and it is often safe enough for swimming. For example, in June and July of 2005 the river basin (top right) had less than the allowed 126 colony forming units of e. coli per 100 milliliters of water (safe for swimming):