10/19/2026
Window mold: one of the most common things we find in U.P. homes—especially lake places and cabins that sit empty for months.
Here's the good news: it looks alarming, but that black staining around the window is usually just surface mold from condensation, not the toxic "black mold" (Stachybotrys) that makes headlines. On a hard surface like a window frame, it's often something a homeowner can clean up themselves.
Why it happens up here:
Cold windows + humid indoor air = condensation collecting on the sill. A home that sits vacant with no airflow gives it time to grow.
The real fix is controlling the moisture—better ventilation, running a dehumidifier, and keeping an eye on your windows through our long, cold season. If it keeps coming back after you clean it, that's a sign of a bigger moisture problem worth looking into.