Mundane astrology is a branch of astrology that involves the application of astrological principles in order to study large groups of people, such as cities and nations.
Whereas natal astrology is restricted to studying the lives of individuals, mundane astrology is used to study groups. This involves things such as studying long-term astrological cycles involving the outer planets, or sometimes specific techniques such as the Aries ingress chart.
Mundane astrology has also sometimes traditionally been applied to the study of natural phenomena such as predicting the weather or earthquakes.
Mundane astrology is usually classified as one of the four main branches of astrology, and it is regarded as the oldest branch.