The Senones Trachyte, a type of volcanic rock, can be used for exterior applications in very humid climates. Trachyte is known for its durability and resistance to weathering, making it suitable for various outdoor uses. However, it is always recommended to consult with a local architect or construction professional who is familiar with the specific conditions and requirements of the region before using any specific stone for exterior applications in a humid climate. They can provide more accurate advice and guidance based on the local climate and other factors.