What temperature and humidity should a vacant condo in South Florida be kept at?
Set the thermostat between 74°F and 78°F and keep relative humidity below 55 percent. Above 60 percent, mould can establish on drywall, leather and fabric within days. A thermostat setting proves nothing on its own — what matters is a measured interior reading taken while the property is closed.
A closed Florida property has no air movement and no occupants opening doors, so the air handler is the only thing removing moisture. Set too high, the unit barely cycles and humidity climbs; set too low, you pay for cooling you do not need and risk freezing the coil. Between 74°F and 78°F the system runs long enough to dehumidify without running constantly.
Relative humidity is the number that actually predicts damage. Below 55 percent almost nothing grows. Between 55 and 60 percent you are in the margin. Above 60 percent, mould begins on drywall paper, leather furniture, artwork and inside closets — often in the rooms furthest from the return air vent, which is exactly where nobody looks.
The failure mode owners miss is that the thermostat can read 76°F while the property is at 68 percent humidity, because the air handler has failed, the drain line has clogged and the system shut itself down, or a window seal has gone. That is why every Hugo Keys visit records a measured temperature and humidity reading and puts both in the report with a timestamp.