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.
Use this link to the old Metye version instead: reg.bom.gov.au/australia/meteye/
higher resolution than the new site.
If i didn't know better i'd say they've gone their separate ways. Seabreeze used to follow the BOM predicted temps (at least) seabreeze has fri being 35 degrees, bom has it at 24 degrees.
BOM are on drugs. 24 max 
given they overstate the wind so they can't be liable when an idiot tries to take a 3m tinny to rotto, how's the temp forecast looking .? Oh let's go hiking in the bush tomorrow with no water cos it is only 24deg
For what it's worth, sailed Dutchies from 3-6ish & was on 5.3, could have easily changed down. Gusts 25+ with a few wobbles in the lulls but generally a good, solid outing. Reckon SB forecast was pretty much on the money for the arvo
