I live in the SW where elastomeric paints over stucco are common. My brother in Florida was told that elastomeric paint does not do well in that heat. Are there limitations on elastomeric usage?
Elastomeric coatings are common in Florida, both residential and commercial uses. Once dry this coating will be fine. Your brother just needs to get hold of a good local painter.
Applying elastomeric paints in excessive heat isn't recommended. There is a way to get around this limitation if this is stucco; wet down the stucco wall before application. This is counter-intuitive but many manufactured do recommend doing this and it does work.