Will a wet ceiling dry on its own?

Sometimes, on a small surface stain. In Myrtle Beach's 70 to 75 degree summer dew points, drywall stays wet much longer than inland. The EPA's 24 to 48 hour mold window shrinks at 80 percent humidity and 75 degrees. At 60 percent humidity, the same drywall takes 10 to 14 days to dry. Run a box fan on the spot, a dehumidifier in the room, and target 50 percent on a hygrometer. Pull attic insulation back and check the topside. Wet fiberglass holds water for weeks and re-wets your drywall. If the stain is bigger than a dinner plate, sagging, or soft to the touch, it's not drying on its own. Cut it out and find the roof source.