A discussion of what constitutes “heavy weather” with particular emphasis on wind wave generation and the factors affecting wave height and lengths including the effects of winds against currents and water depths. Analysis of the potential for rogue or unusually high waves will also be discussed. Primary sources of information allowing anticipation and timely preparation, including both online links and personal observations, will be presented and evaluated. This information together with consideration of vessel and crew characteristics provides the basis for selection of optimum management protocols ranging from simple reefing to heaving to, streaming drogues, bare poles, or some combination. Examples of each will be provided. Both sail and power boat needs will be considered.