Megastorms are intense, prolonged atmospheric river events that drench broad areas of the West Coast with tens of cubic miles of rain and snow in a matter of weeks. Using facts and the latest forecasts from leading researchers, this book describes megastorm history and science, their known and expected impacts, hazards, and costs, and the estimated (and increasing) odds that one will occur in any year. California is particularly susceptible to megastorms; one in 1862 remains America's greatest natural disaster. These pages will raise your awareness and understanding of what to expect, and explain how individuals, families, households, and communities can prepare to safely ride out weather impacts more extreme and extensive than living Californians have ever seen. Practical advice for personal preparation allows the reader to proceed with greater confidence. Suggestions and proposals for action by community organizations and public agencies are also presented.