A pretty basic question from a newbie to the forum:

Which online weather forecast do members think gets nearest to the mark?

In the absence of a forecast for Borth, the candidates would seem to be:
Aberystwyth (Met Office), at <http://www.metoffice.gov.uk/weather/uk/wl/aberystwyth_forecast_weather.html>
Aberystwyth (MetCheck), at <http://www.metcheck.com/V40/UK/FREE/today.asp?zipcode=Aberystwyth>
One of the services on Aberdyfi .com, <http://www.aberdyfi.com/metcheck.asp>

For example, the Met Office forecast for Aberystwyth [time / wind speed (mph) / gusts] for the rest of today is:
13.00 / 16 / 27
16.00 / 17 / 27
19.00 / 17 / 27
22.00 / 18 / -

while MetCheck's is:
13.00 / 11 / 13
16.00 / 10 / 12
19.00 / 8 / 10
22.00 / 7 / 9

Slightly different, I hope you'll agree, and the difference in the gusts making the world of a difference to a pottering-about dinghy sailor like me, if not to the adreneline-junkie kite surfers etc. that probably make up the majority of members!

All the best.

I always find Windguru to be the most accurate and it has a Borth forecast and I've even adjusted it to take into account local variations:

WindGuru Borth

Al.