Just curious as to which online weather site you guys think is the most accurate? I've been looking at a few but there's always conflicting reports. Is there one out there that is simply more accurate than the rest?
Most accurate - look out the window 
But seriously, i tend to use 3 or 4 forecast sites and try and decypher from the information.
BOM.gov would have to be one of the better equipped sites to use.
There is always going to be an element of chance, the further out you predict.
Generally the Southern Ocean Barometric forecast can provide you with a reliable outlook, as long as you can understand the high and low pressure movements and the particular effects each one produces.
Thats what i use anyway.
Hope that helps.
Looking out the window is good as mentioned above.
Personally I think forecasting is best done by yourself looking at the synoptic pressure charts. For example a big high pressure system drifting around Lord Howe to Norfolk Island, will deliver strong NE seabreezes down the NSW coast. No doubt about it.
However I get lazy and just look at the Seabreeze arrows.
Like the OP I'm still trying to figure out which are most reliable... tend to keep a track of their predictions versus actuals. Find Windguru most consistent to their predictions.
It really depends on where you live, and the time of the year -> in the Melbourne area, I find it not accurate enough, while windguru is a little better.
Nothing is all that useful for predictions, as Melbourne heads into the doldrums (April / May).
As an example the Seabreeze arrows are showing 25kn easterly Saturday arvo, for Melbourne - I wouldn't rely on that forecast for sailing at the top of the Bay. But it is likely to blow 25kn at Sandy Point (2.5hrs away) and maybe 15-20 at Inverloch (2hrs away).
Generally speaking, the BOM isn't useful as they use too many generalisations, but the "wind and wave" forecasts for Port Philip Bay, are somewhat useful for predicting a few hours ahead.
Windguru I find particularly useful. Find a location on Windguru near to where your sailing and correlate against temp, and if frontal or overcast or not.... Use for Boggy Lake and for Lake George and have not lucked out yet if under 48 hours.
marine wind forecast
www.bom.gov.au/marine/wind.shtml
Usually the most accurate predictor for the Perth area as it shows the windstrengths for different areas of the coast and river (which are usually quite different) whereas the forecasts are just an average.
Local BOM marine forecast I think is most accurate. Also use Meteorology.com.au 7 day local forecast to get an idea of the weekly trend, their wind speed forecast appears to be on the mark much of the time though think they predict only the 'average' km/h speeds without peak gusts (usually compare with same BOM forecast for area and period to get best synopsis).
gday,i generally use three or four sites but as the other replies you have had,my advice would be to watch for two very important cylces,this is off the coast of fremantle anyway and they are any troughs pushing down from the north and our typical high approaching from the west keep an eye on there movement and the weather sites at the same time,and when it all starts to look good,and stays where it should and the previous recorded days weather did what it said it should,get ready to ring the boss and tell him you wont be in,cheers seadog67
Stormsurf has been great for our region in SA as we have to do a fair bit of travelling, last couple years we normally have had about 90-95% success rate on trips, the model is easy to correlate with the high and low patterns to check whether it will work. Select your region and the click on Wind or Surf to wacth the patterns go thru www.stormsurf.com/.
Ps we have noticed it is 6hrs out, so if timeframe shows 12midday it is actually 6pm
For observations, whatever station is nearest is best.
Many yacht clubs have weather stations and cams linked to their web sites. A bit of browsing on maps and the net will find them.
At my local spot we have a BOM weather station 6km offshore, and an airport about 10km away. I find that splitting the difference between the two works well.
For short term forecasts the BOM is best. I look at the local waters forecasts.
BOM has a simulation that predicts the winds and presents the results graphically. It's been surprisingly accurate in my area (Melbourne).http://www.bom.gov.au/nsw/forecasts/localwaters.shtml?type=WindMag
I like W1llyweather for long range forecasts. It's not accurate but you can get all the interesting stuff on a single page (tides, wind, temp, rain etc)
Bom uses 3 weather models and takes the average of the three predictions, all the other sites use just one.
That info is from Ask Huey, but I learnt that at a pretty hazy night at Gerroa Fishos, so numbers and factual accuracy may vary.
The Windfinder and Windguru graphic predictions are pretty good for a quick, rough forecast up to a week ahead. They are able to be customized to specific locations and with Windguru you can add modifications based on local knowledge.
The disadvantage of those predictions is that they are based on a single computer model. (GFS)
The advantage of them is that they are free.
Predictwind, a NZ based company, shows a bit more detail with one hour forecasts and high resolution maps.
Another advantage of Predictwind is that they show both the GFS and CMC models. If they both agree closely you can have more confidence. If they don't, its anyone's guess. 
To get the Predictwind forecasts more than a day ahead you have to pay a subscription.
For when it really matters (isn't that always?) I subscribe to Weatherzone (pro) for $5 a month. This gives me access to some amazing information from six separate computer models! 
There I can study the state sized predicted maps and much more up to 16 days ahead, although anything more than 4 or 5 days is ahead is not usually all that reliable. What does help a lot is comparing the models. Again, if they all tend to agree closely you have probably hit the jackpot. If they don't, well, as I said before, it can be anyone's guess.
I highly recommend weatherzone pro, especially if you learned to read a weather map in school.
i use a few also.
gfs is free here, it handles extended and allows you to take slices at multiple pressures.
www.wunderground.com/wundermap/?zoom=4&rad=0&wxsn=0&svr=0&cams=0&sat=0&riv=0&mm=1&mm.mdl=GFS&mm.type=SURPRE&mm.hour=0&mm.opa=100&mm.clk=0&hur=0&fire=0&tor=0&ndfd=0&pix=0&dir=0&ads=0&tfk=0&fodors=0&ski=0&ls=0&rad2=0
for standard gfs where you can go more local. for some reason the gfs data is not displaying right now.
forecasts.bsch.au.com/forecast_machine.html
for the european model ecmwf you can get it here.
www.ecmwf.int/products/forecasts/d/charts/medium/deterministic/msl_uv850_z500!Wind%20850%20and%20mslp!0!Australia!pop!od!oper!public_plots!2010122500!!/
the bom marine forecast model uses only ecmwf up until 3 days out and then switches to it's own model which is access.
www.bom.gov.au/marine/wind.shtml
i also find the bom marine models very accurate at 2 days out.
some other models i use are
tropic.ssec.wisc.edu/real-time/windmain.php?&basin=austeast&sat=wgms&prod=wvir&zoom=&time
this one has pretty much all of them
28storms.com/cyclone/
www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=aupa&MODELL=cmcens&MODELLTYP=2&VAR=prec&HH=6&BASE=-&WMO=&ZOOM=0
Thanks heaps for the replies. Now I have 34 weather sites saved in my Favourites...lol
