Mexican terracotta can be used for exterior applications in humid climates, but there are a few considerations to keep in mind. Terracotta is a natural clay material that is porous and can absorb moisture. In very humid climates, where there is a lot of moisture in the air, the terracotta may absorb more moisture and potentially cause issues such as mold, mildew, or efflorescence.

To mitigate these issues, it is important to properly seal the terracotta with a high-quality penetrating sealer specifically designed for terracotta. This sealer will help protect the terracotta from absorbing excess moisture and prevent the growth of molds or mildews. The sealer should be reapplied periodically to maintain its effectiveness, especially in areas with heavy rains or high humidity.

Additionally, it is crucial to ensure proper installation and maintenance of the terracotta. This may include proper drainage, regular cleaning, and periodic inspections to identify and address any potential issues early on.

Overall, with proper sealing, installation, and maintenance, Mexican terracotta can be used effectively for exterior applications in very humid climates. However, it is recommended to consult with a professional or supplier familiar with terracotta in your specific climate to ensure the best practices are followed.