I first encountered this word while in my studies at St. Bens. It is a word used in metaphysics, the philosophy of nature, and in theology. It is used to define phenomena or events which fall outside of the normal or ‘natural’ but still happening by the agency of some created being (including spiritual beings).
The discussion of preternatural events vs supernatural events typically comes about with scrutinizing the authenticity of miracles – to determine if they occurred by divine, ‘supernatural’ agency or by human or demonic trickery. In other words, what a layperson would discern as miraculous or magic – the two are not the same. This usage has led to the term being linked almost completely with the occult and the demonic.
Then there are phenomena which historically were considered preternatural. For example raining of frogs or fish, at one point in time was attributed to demonic action. Today we believe that these rains are the result of tornadic waterspouts which pick up fish or other aquatic creatures from a lake or river only to drop them several miles away.
My caution is to be sceptical about such ‘miraculous’ events or phenomena.