Meteorology is not one of the most discussed topics in Paracelsus studies, although it is closely linked to both Paracelsus' medicine and cosmology. Furthermore, it appears to be at the very core of Paracelsus' famous matter theory of three chymical principles, mercury, sulphur and salt, known as the tria prima . By discussing prominent examples of Paracelsus' explanations on how the tria prima operate within the stars, this article shows how the Swiss physician conceived meteorology within his own body of knowledge, obviously constructed in opposition to the Aristotelian-scholastic tradition, how he based it on a peculiar interpretation of the Biblical creation story, and made it the proper laboratory of his chymical matter theory, applying it first systematically to the field of natural philosophy, especially to celestial phenomena, even before using it for his medical theory in his later writings.