The practice of weather forecasting underwent a crucial transformation in the Middle Ages. Exploring how scientifically-based meteorology spread and flourished from c.700–c.1600, this study reveals the dramatic changes in forecasting and how the new science of 'astro-meteorology' developed. Both narrower and more practical in its approach than earlier forms of meteorology, this new science claimed to deliver weather forecasts for months and even years ahead, on the premise that weather is caused by the atmospheric effects of the planets and stars, and mediated by local and seasonal climatic conditions. Anne Lawrence-Mathers explores how these forecasts were made and explains the growing practice of recording actual weather. These records were used to support forecasting practices, and their popularity grew from the fourteenth century onwards. Essential reading for anyone interested in medieval science, Medieval Meteorology demonstrates that the roots of scientific forecasting are much deeper than is usually recognized.