The Best Thermostat Settings for a Florida Summer

Start with a number, then adjust for your house

The widely cited guidance is 78°F while you are home, and most South Florida households land somewhere between 74 and 78. Anyone who tells you there is one correct number is selling something. What matters more is that the number is steady and that humidity is under control, because a house at 76°F and 50% relative humidity feels far more comfortable than the same house at 74°F and 65%.

Every degree you raise the setpoint reduces run time and cost. The honest trade-off is comfort, and that is yours to make — not something a blog can decide for you.

The biggest myth: switch it off when you leave

In a dry climate, shutting the AC off while you are at work saves money cleanly. In South Florida it often does not, and here is why: while the system is off, the house absorbs both heat and moisture. Walls, furniture, carpet and drywall all take on humidity. When you come home and drop the thermostat, the system has to remove the heat and pull all that moisture back out — and moisture removal is slow.

The result is a system that runs hard for hours, a house that stays clammy well into the evening, and in the worst cases enough sustained indoor humidity to encourage mould. Setting back a few degrees while you are out is sensible. Switching off entirely, in August, in Florida, usually is not.

Set the fan to AUTO, not ON

This one is easy and it costs nothing. With the fan on ON, the blower runs continuously — including after the compressor stops. That blows air across a coil covered in condensed water and evaporates it straight back into the house. You paid to remove that moisture; the fan puts it back.

AUTO lets the water drain away as designed. Unless a technician has specifically told you to run continuous fan for a filtration or air-balance reason, AUTO is the right setting in this climate.

Things that genuinely help

• A small, consistent setback — two to four degrees while out, not off.
• Ceiling fans in occupied rooms only. Fans cool people, not rooms, by moving air across skin. Running them in empty rooms just adds motor heat.
• Close blinds on the sun side. Solar gain through west-facing glass in the afternoon is a real load, not a rounding error.
• Keep the filter clean. A loaded filter chokes airflow, which lowers capacity and pushes run times up.
• Keep the outdoor unit clear. Hedges, fence panels and stacked garden gear all restrict the airflow the condenser needs to reject heat.

Things that mostly do not

• Cranking it to 68 to cool faster. The system has one speed; it does not try harder at a lower number. You just overshoot and pay for it.
• Closing vents in unused rooms. On a ducted system this raises static pressure and can reduce airflow across the coil, hurting efficiency and, in bad cases, freezing the coil.
• Scented filters and high-restriction filters bought on instinct. Filtration matters, but the wrong pressure drop costs you capacity.

When the thermostat is not the problem

If you have to set 71 to feel comfortable at what should be 75, the thermostat is reporting a symptom, not causing it. Common real causes: low refrigerant charge, a dirty condenser coil, leaky or undersized ductwork, poor attic insulation, or a system that was never sized to the house. Chasing it with the setpoint just raises the bill while the underlying fault stays put.

The same goes for a house that is cool but damp. That is a dehumidification problem — usually short cycling from an oversized system — and no thermostat setting fixes it.