Yes, China Grey Slate can be used in exterior applications in hot climates. Slate is a natural stone and is known for its durability and resistance to heat, which makes it an ideal choice for outdoor use. However, it is important to ensure that the slate is properly installed and maintained to prevent any damage or discoloration over time due to exposure to the elements. Additionally, it is recommended to choose lighter colored slate in hot climates as it will absorb less heat and prevent the surface from becoming too hot.