This could create quite a bit of discussion. Here’s my 2 cents:
My mental picture has the NWish wind blowing down the coast, due to the Pacific High well offshore. As the wind goes by Point Arena and/or Point Reyes sticking out into the Pacific, a turbulent eddy can be
created behind the point(s) on the coastline side, just as would happen if were talking about the current flowing down the coast—you would get a current eddy behind the point. That eddy means that the stronger flow of air is offshore more than if the eddy
were not there. So to enter the bay, the wind must turn more than it would without the eddy—picture the eddy extending down almost to the Golden Gate. The strong air offshore would need to make a 90 degree turn to enter the Gate. Inertia of the air being
what it is, that’s hard to do, resulting in a weaker flow.
Starting with a NNW wind going by Point Arena, I think the wind would trip turbulent and create an eddy behind the point. As you shift the breeze more westerly (say, NW), the wind would skate by Point Arena
without creating much of an eddy, but would then be tripped up by Point Reyes, creating an eddy near the Golden Gate, and perhaps in front of the Golden Gate. As you shift the wind more westerly yet (say WNW), the wind skates by Point Reyes without much of
an eddy, and the wind is more easily able to curve into the bay.
