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.