Methods of Weather Forecasting in the Islamic Mashriq during the Abbasid Era (The Zodiac as a Case Study)

Abstract

The study of the Islamic astronomical heritage in the regions of the Islamic Mashriq reveals that astronomers relied on observing the movements of celestial bodies and monitoring the changes affecting them, and on correlating these observations with changes in weather conditions, with the aim of predicting atmospheric fluctuations. This demonstrates that most of these predictions were based on observation, systematic monitoring, and inductive reasoning, rather than on occult astrology grounded in philosophical interpretations of nature.

In this context, the zodiacal signs constituted one of the most important tools employed by astronomers to determine the positions and conjunctions of the planets and to associate them with climatic changes, particularly the Sun and the Moon, as they were regarded as the celestial bodies exerting the greatest influence on weather conditions. Their motions were used to determine the beginnings of the seasons and the cycles of heat, cold, and drought, as well as other partial phenomena such as rainfall, snowfall, and the occurrence of winds.

To facilitate the process of observation, astronomers adopted a division of the twelve zodiacal signs according to the four elements (fire, water, earth, and air), which they termed the triplicities. The fiery signs were considered indicative of heat, dryness, and aridity; the watery signs of rainfall and humidity; the earthy signs of seasons of growth and vegetation; and the airy signs of winds and storms. However, this classification represents a theoretical division rooted in natural philosophy rather than one firmly based on observation, experimentation, and long-term climatic induction. This explains why some of their predictions occasionally conflicted with the actual climatic characteristics of those zodiacal signs.