Homes with stucco exteriors are typically found in warm areas where it’s often warm and humid. This type of climate can become a breeding ground for mold growth. Stucco exterior walls are generally made from cement plaster. This porous material often absorbs stains caused by mold and mildew. Mold often has a brown or black hue to it but can also develop as orange and red spots. Cleaning mold from your stucco exterior is a rather simple process that can be completed in an afternoon. You can remove these stains by following some simple steps.