Yes, Mexicos Terracotta Onyx can be used for exterior applications in very rainy climates. Terracotta Onyx is a type of natural stone that is known for its durability and resistance to weathering. It is capable of withstanding rain, moisture, and extreme weather conditions. However, it is always recommended to consult with a professional or supplier who can provide specific information and guidance on the suitability of the stone for your particular climate and application.