Dry climate, wet spots
Outdoor air in the Coachella Valley is dry for most of the year, so indoor moisture problems usually trace back to a specific source rather than general humidity. That makes the early signs worth paying attention to.
Signs to watch for
A musty or earthy smell that is stronger in one room, or when the air conditioning first starts. Staining, bubbling paint or soft drywall on ceilings and lower walls. Water or rust marks around the water heater, laundry connections or under sinks. Condensation or dark spotting around supply-air vents during long cooling periods. Damp baseboards or flooring on walls next to irrigated beds or lawn.
Homes that have been closed up for the summer deserve a careful walk-through on return — slow drips can go unnoticed for weeks.
What to do next
Stop any active leak you can safely reach, dry what you can, and avoid disturbing suspected growth. Take photos with dates. If the source is not obvious, or the smell persists after drying, a moisture inspection can locate where the water is coming from.