SB is just the ocean isnt it? I dont think its as specialized as the BOM site that goes into detail about other areas.
My understanding is they are different models. BOM is a more localised forecast. In NSW for example the Seabreeze is a good indicator to what the wind will be doing in general but BOM, especially Meteye, will giver you a detailed forecast that takes local topography into consideration.
Looking at the 35 degree forecast alone I would think a strong Seabreeze is very unlikely. I haven't temps in the mid to high 30s and a strong Seabreeze at the same time.
Use the marine wind forecast as it gives a good idea on where the wind will be.
www.bom.gov.au/marine/wind.shtml?unit=p11&location=wa-per&tz=AWST
Look at the prognosis maps and you'll see why there's uncertainty. There's another trough coming in and hard to predict how that affects the wind so anything can happen.