The weather is a staple of small talk, the app on our smartphones, and often the first thing we check each morning. It is also the inspiration for one of the most expansive machines human beings have ever constructed—but what is this 'weather machine' and who created it? In a quest to understand how the forecast works, Andrew Blum visits old weather stations and watches new satellites blast off, and follows the dogged efforts of scientists to create a supercomputer model of the atmosphere and traces the surprising history of the algorithms that power their work. We have quietly entered a golden age of meteorology, Blum suggests here, but although our tools allow us to predict weather more accurately than ever, we haven't learned to trust them.