Yes, Mexican Terracotta can be used for exterior applications in very sunny climates. However, it is recommended to apply a sealant to protect the terracotta from UV rays and other weather conditions. The sealant also helps to preserve the color and prevent the terracotta from cracking or fading over time. It is important to understand that maintenance is required to keep the terracotta in top condition, including regular cleaning and reapplication of sealant.