An essential pocket-sized primer that equips sailors and outdoors enthusiasts with the knowledge to read and predict the weather. Weather determines when we sail, where we sail to – and whether we arrive safely. This essential pocket-sized guide explains how the weather works and how to understand and use all forms of marine weather information, whether for day sailing or long coastal and offshore passages. This new edition updates availability and usage of computer-generated forecasts with a glimpse into the AI future. Climate change impacts on sailors are described and there is a scientifically correct description of the Coriolis effect. With practical explanations, helpful diagrams and photographs, this is the ideal aide-memoire for skippers and crew, especially those studying for their Day Skipper and Yachtmaster exams.