Please wear something that you enjoy wearing and that you feel brings the energy/tone that you want to contribute. We're not looking for formal or a theme, just happy.
That said, here's what to expect for weather:
It is unlikely to be raining. We will move the ceremony inside if it is.
The average high for the day is 70 degrees F, the low 52 degrees F.
The 10-day forecast is here.
If you would like more detail about the probable weather, you can check out Weatherspark.
For less applied but interesting information on our local weather, visit the Cliff Mass Weather Blog. It might not give you any better idea of what to pack, but you'll know more about how the weather around here works.