This chapter provides definitions of contrasting classical and medieval approaches to meteorology. It outlines the relevant works of Aristotle, as well as the means by which selections from these were transferred to Roman writers. The roles of Pliny and Virgil are considered, together with their own reception by early medieval writers. A key point is that patristic writers, especially Augustine, integrated this knowledge of the natural world into Christian teachings on cosmology. However, Aristotle’s arguments on meteorology were primarily transmitted to Latin Europe in Islamicate versions, and came accompanied by new information on astronomy. The chapter then offers an account of the transition from classical, theoretical models of climate to more detailed calculation of planetary movements and their alleged meteorological effects. An important argument is that early medieval scientific work is often presented in diagrams and tables, themselves found in monastic works on the ecclesiastical year, and are easy to miss or underestimate.

Chapter 7 considers astrometeorology as an established branch of knowledge, within the context of fourteenth-century developments in astronomy and technology. Mechanical clocks were prominent products of these advances, as were more accurate astrolabes and planetary tables. Most successful of the latter were the Alfonsine Tables, used by the authors of new and more ambitious treatises of astrometeorology, such as Firminus de Bellavalle. The chapter analyses the new approaches taken by inventors like Richard of Wallingford and scholars like John of Eschenden, and traces the growing prominence of Merton College, Oxford, in this field. Eschenden’s fame as a forecaster was boosted by his claim to have predicted the great plague of 1348. Related to this is the survival of his weather forecasts for 1348 to 1374. The chapter considers the rise of weather observation, and the survival of records from Lincolnshire, Oxford, Wurzburg and Basel, as evidence of a drive to give astrometeorology an empirical backing. It concludes that astrometeorology grew as an area of expert practice, despite the attacks that critics such as Nicole Oresme made against the reliability of all forms of astrology.

Chapter 3 gives an account of the transmission of Islamicate meteorology into Northern and Western Europe. An early phase was the collection and study of the texts known as the Alchandrean Corpus, which provided short introductions to topics within astronomy and mathematics. The chapter then considers twelfth-century translations of more advanced works, and especially of treatises on weather-forecasting. The contributions of Petrus Alfonsi, and the reception of Latin translations of Arabic versions of the works of Ptolemy, are discussed. The chapter argues that it was this period that saw the creation of Latin, Christian forms of astrologically based weather forecasting. Moreover, this was no transitory fashion, and the new, astrometeorology remained dominant until the seventeenth century. Central to this new science was the application of fundamental works by Ptolemy, and this is considered in detail. The final part of the chapter gives an outline of the works of Islamicate astrometeorology that were translated into Latin, and especially of the theories of al-Kindi. The conclusion is that Latin writers and translators searched out works on weather forecasting, and rapidly began to produce their own versions.

Chapetr 4 traces the reception and adaptation of Islamicate meteorology by writers and scientists in Northern and Western Europe. Fundamental to this was the growing body of planetary tables, based on versions of Ptolemy’s work, which made it possible to calculate the positions of the planets with much greater accuracy. The chapter traces the works of Latin astrometeorology that drew on this ability, and gives outlines of the processes involved in making actual weather forecasts, according to rival methods. Pioneers were Hermann of Carinthia, Robert of Ketton and John of Seville, who all made translations and then issued new treatises on the subject. Manuscript evidence for the transmission of this new astrometeorology is discussed. The roles of astrological textbooks, especially the Book of Nine Judges, are considered. The concluding part of the chapter weighs up the popularity of astrometeorological forecasting across Europe by the early thirteenth century, and argues that it was closely associated with the emergence of a new, highly technical, scientific discourse.

This chapter begins with an account of the roles of Charlemagne and Alcuin in supporting the study of computus and astronomy in the Carolingian Empire. It then offers an outline of the expanded astronomical and meteorological information found in Carolingian ‘encyclopedias’ of computus. A key problem for users of these collections was the lack of accurate astronomical observations and calculations, which enforced continuing dependence on lists of short-term ‘signs’ of coming weather, mostly derived from Pliny. One attempt to improve the range of knowledge available took the form of beautifully illuminated versions of Aratus’ long poem, in volumes known as Aratea. The dissemination of this body of information is traced through analyses of surviving manuscripts, which demonstrate the resources being devoted to the subject across mainland Europe. Separate consideration is given to Anglo-Saxon England, where Viking conquests and wars had caused serious disruption, and where the teaching of Abbo of Fleury, and his pupil Byrhtferth, was crucial. The chapter argues that possession of superior astronomical and meteorological knowledge was highly vaued by rulers in both secular and spiritual spheres.

The Conclusion traces the importance of astrometeorological forecasts from the seventeenth century onwards. It finds surprising evidence that they finally disappeared only in the nineteenth century, despite increasing criticism. In fact, one of the attackers mourned the continuing high sales of Moore’s almanac in the 1830s. A central finding is that the increasing rejection of astrology in the eighteenth century, and the attacks on astrometeorology, led to the absence of any accepted basis for making weather forecasts. This problem, together with ongoing demand for knowledge of coming weather, led to the revival of old-fashioned weather-signs. The support given by Tycho Brahe and Johannes Kepler to both astrometeorology and the keeping of waether records is considered, as are early modern treatises on weather prediction. A detailed study of English 18th-century almanacs shows use of weather journals and instruments such as barometers, alongside traditional astrometeorological methods. The final conclusion is that it was only the production of FitzRoy’s new, ‘practical’ system of forecasting the weather that finally ended the age of medieval meteorology.

Chapter 5 traces the evidence for the practice of astrometeorology by scholars and professionals in the service of the European elite. This phenomenon faced criticism from those who feared the rise of judicial astrology and the associated threat of demonic intervention. The chapter analyses the level of meteorological knowledge displayed by scholars such as William of Conches, adviser to Geoffrey of Anjou. William knew works attributed to Masha’allah as well as Seneca, and deployed the new, scientific terminology that spread in the twelfth century. A key point is that works like William’s depict secular rulers as keenly interested in understanding and predicting the weather. From this the chapter moves on to the more advanced astrometeorological teachings of Abraham Ibn Ezra, a Jewish scholar from al Andalus who travelled across Italy and Spain. One of his innovations was to provide tables of mathematical values to be applied to astrometeorological configurations, making forecasting much simpler. This was to be followed by others in the thirteenth century. The chapter ends with comment on the scarcity of surviving twelfth-century copies of these works.

This chapter first explores how early medieval writers, and especially Isidore and Bede, made fundamental contributions to a new understanding of the natural world and its workings. They both quarried classical works for factual information and empirical observations, and placed these within a Christian cosmological model. An outline is given of the monastic science of ‘computus’, which was fundamental for teaching on natural philosophy and for theories about the weather in particular. Summaries of introductory works by both Isidore and Bede demonstrate their respective meteorological models; Bede’s views on the powers of the planets are covered in detail. Special attention is given to Bede’s The Reckoning of Time and the complex information on astronomy and meteorology which it expounds. An important conclusion is that Bede produced an understanding of weather as the intelligible and predictable result of astronomical and climatic factors. Overall, the chapter argues that classically derived natural philosophy and Christian cosmology were successfully integrated, and that the two together provided the basis for a new approach to weather and its prediction.

Chapter 6 traces the spread of astrometeorology and detailed weather forecasting amongst the lay and ecclesiastical elite. It discusses the distinctions made between varying forms of astrology, before analysing a treatise attributed to Robert Grosseteste. This offers a worked example of a weather forecast for 15 April 1249. The chapter argues that such forecasts were in accord with other works by Grosseteste. It goes on to consider the place of accepted forms of astrology in thirteenth-century university study. An important point is that Aquinas’ Summa Theologiae established weather forecasting as distinct from divination. Equally important is the evidence of the Mirror of Astronomy attributed to Albertus Magnus. This discusses astrometeorology in detail, and gives a list of approved works on the subject. The chapter concludes that this endorsement was very important, given the growing concern about necromancy and divination. Analysis of contemporary enclyclopedias demonstrates the authors’ very cautious acceptance of the basics of astrometeorology. In contrast, secular rulers such as Frederick II openly employed astrologers like Michael Scot and Guido Bonatti, whose contributions to astrometeorology are discussed.

Chapter 8 sets out the evidence for the growing prestige of, and demand, for, astrometeorological forecasts in the fifteenth century. It traces the establishment of chairs in astronomy and astrology in universities old and new across Europe, and looks at the forecasts issued by the holders. The rapid creation of annual almanacs, based on these forecasts, and the demand for affordable, printed copies, are outlined. The important works of Abraham Zacut, Regiomontanus, the Laet family, and Leonard Digges, are all discussed in detail. The numbers of printed editions, their price levels, and their success, are all considered as evidence of demand for updated, ever more accurate, versions of astrometeorology. Digges’ work is shown to have addressed a readership keen to make their own forecasts. The conclusion is that it was in the sixteenth century that astrometeorological weather forecasts reached their peak, even though changing intellectual fashions saw shifts in the great names claimed as founders of the science. Moreover this popularity was to last well into the seventeenth century.