The Short Answer
No government agency publishes an official ranking of states by mold. Mold risk tracks moisture, so states with high year-round humidity, heavy rainfall, and frequent tropical storms, such as Florida, Louisiana, Hawaii, Texas, Mississippi, and Alabama, are generally considered the most mold-prone.
Why there is no single answer
Mold is not tracked state by state the way weather or disease is. Rankings you see online are usually based on climate data, insurance claims, or survey estimates, and they vary depending on the method. What they agree on is the underlying driver: moisture.
What makes a state mold-prone
- Sustained high humidity for much of the year.
- Heavy seasonal rainfall.
- Frequent hurricanes, tropical storms, or flooding.
- Warm temperatures that let mold grow year-round.
- Building practices that trap moisture, such as slab foundations and closed-up air-conditioned homes.
Where Florida fits
Florida checks nearly every box. It has humid subtropical and tropical climates across the state, a long hurricane season, intense summer rain, and homes that rely on air conditioning to stay dry. Coastal and low-lying areas face added flood risk. That combination makes moisture control a year-round priority rather than a seasonal one.
What matters more than the ranking
Your risk depends far more on your specific building than on your state. A well-maintained Florida home with good humidity control can stay dry for decades, while a home in a drier state with a hidden plumbing leak can develop serious growth. The building, its moisture history, and how it is maintained tell the real story.