Critical to our cruising life is feeling confident with the weather forecasting modules. There are so many websites to choose from, but we tend to use these ones for our Australian travels. All these below are nil cost to use.
BOM - this is the Bureau of Meteorology We find BOM fantastic for passage planning as it has the weather by coastal regions all over Australia.
Willyweather is a very good for your immediate local area.
Seabreeze is another localized reporting module. We often use this website to see a little bit more of a global view.
Predict Wind is another favorite of ours when passage planning. It uses two different data sources: PWG & PWC differences of the two explained here. Loads of information on the one page. If you wish to use a paid version it does have some very good passage planning options.
Once we move over to Indonesia, Singapore, Malaysia & Thailand (apart from our Sailmail) we plan on using these websites;
Weather Online UK
World Weather Information
BOM for severe weather reporting alerts
Global Tsunami warnings
Meteorological Service Singapore
Malaysia Met Bureau