1. An event or phenomenon that happens in nature without human intervention; something that occurs naturally as part of the natural world
Rain is a natural occurrence in tropical regions during monsoon season.
A chuva é uma ocorrência natural nas regiões tropicais durante a estação de monção.
2. A common or expected event that happens regularly in nature
The migration of birds is a natural occurrence every spring.
A migração de aves é uma ocorrência natural a cada primavera.