When the outside temperature drops, too much moisture is a bad thing. If the humidity builds up too much, condensation on the windows can eventually bead up and roll down until it soaks into the window frame. All throughout the winter months, this water can leak back behind the wall below the window, leading to wood rot and mold. Not only is mold a dangerous situation for your family in the home, but the damage this excess water in the air can leave behind your walls can get expensive.