The temperature and moisture level of a dogs nose will vary throughout the day. Your dog uses its nose to help cool itself, so if your dog is hot then it will sweat (and lick) its nose so that the evaporating moisture helps cool it down. If you touch its nose at this time it will be cold and wet. If your dog feels like its at the correct temperature then it then its nose will feel dry and warm. It is however unusual for a dogs nose to be hot and dry, this is sometimes a sign of illness.