Weather - we can't avoid it. Good or bad it's always with us but with study and observation we can better prepare and, at times, choose the conditions we'd like to tackle. It can be a complex subject, so we have provided the basic study of weather from our international commercial and recreational, and teaching experience. These are notes and tips for you to consider during passage planning and when underway; across vast oceans for weeks on end or a day sail across a harbour. We've incorporated over forty years of combined knowledge while sailing the world. We've sorted through the technical aspects, simplified them, and included what we feel is important to those wandering the oceans and coastlines on boats. It's a fascinating subject and we hope this helps you better understand that weather forecast adjustments are just one of the many hats mariners wear. Weather forecasts are never going to be perfect, it is our responsibility to interpret, adjust, and prepare.