Your windows have tiny drain holes — and they clog

Look along the bottom outside edge of most sliding and single-hung windows and you'll spot small slots called weep holes. They're there on purpose: rain and condensation that collect in the track need a way to drain out, and the weep holes channel that water back outside instead of letting it pool in the frame.

In Florida they clog easily — dirt, pollen, lovebug debris, and even little insect nests pack the slots shut. Once the water can't escape, it backs up in the track and can overflow onto your sill, seep into the wall, and feed mold. Sealing the holes with caulk to 'stop a leak' only makes it worse.