From roughly May through October, South Florida runs warm, wet, and humid almost every day. That is perfect weather for exactly one thing you do not want: algae and mildew on your house. If your exterior greens up every summer, this is why.
Rain feeds it, it does not clean it
A common assumption is that all that rain should rinse the house clean. The opposite is true. Algae and mildew are living growth, and moisture is their fuel. The daily afternoon storms keep every surface damp, and the heat keeps the growth active. More rain means more green, not less.
Which surfaces get hit first
North-facing and shaded walls. They stay damp the longest and get the least drying sun, so they green up first and worst.
Roofs. The black streaks that spread across Miami roofs are algae, and rainy season is when they take off.
Pool decks and shaded patios. Splash-out plus shade plus foot traffic makes them slick with algae, which is a safety issue as much as a looks one.
How to stay ahead of it
The move is timing, not just reaction. A clean heading into rainy season starts you from a lower baseline, and a clean after it removes the season's growth before it sets into a stain. On a recurring plan, the property never reaches the heavy-growth stage, which keeps each visit light and the house looking right year-round. If the green is already here, a soft wash kills it at the root so it stays gone longer.
Common Questions
Why does my house get green every summer?
South Florida's rainy season runs roughly May through October, and the constant moisture plus heat is ideal for algae and mildew. Shaded, north-facing surfaces green up fastest because they stay damp longest.
Should I wait until after rainy season to clean?
A clean just before and just after rainy season works best. Going into it clean slows the buildup, and cleaning after removes the season's growth before it sets in and stains.
Does rain not just rinse it clean?
No. Rain feeds the growth, it does not remove it. Algae and mildew thrive on the moisture, so more rain means more growth, not a cleaner house.