Florida heat · what to set it on
What Temperature to Set Your AC in Florida
For most Florida homes the published answer is 78°F while you are home (or the warmest setting you are still comfortable at), about 82°F while you are away for the day, and the thermostat fan on AUTO. That is FPL's guidance; FPL's expert pages give a home range of 75–78°F and an away range of 80–82°F, and say each degree you raise it between 75°F and 78°F can save 3–5% on monthly cooling costs. In Florida the fan setting matters as much as the number: Florida Solar Energy Center field data at a 77°F setpoint showed about 50% indoor humidity with the fan on AUTO and 60–65% with it on ON. Leaving the house closed for the summer is a different problem, covered below. If the house is sticky at 78°F, fix the humidity, not the number. Educational only. Not a service page.
Per-degree savings planner
Uses FPL's rule of thumb only: cooling is about 60% of the bill, and each degree raised between 75°F and 78°F saves 3% to 5% of monthly cooling costs. Degrees outside 75–78°F are not estimated. A ballpark, not a bill quote. Saves on this device only.
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Enter your numbers and tap Estimate.
Worked examples: 75°F to 78°F
Same math as the planner: bill × 60% cooling share × 3–5% × 3 degrees. That works out to about 5.4% to 9% of the whole bill.
| Monthly bill | Cooling share (60%) | Estimated saving, 75→78°F |
|---|---|---|
| $150 | $90 | $8.10 – $13.50 a month |
| $200 | $120 | $10.80 – $18.00 a month |
| $250 | $150 | $13.50 – $22.50 a month |
| $300 | $180 | $16.20 – $27.00 a month |
Use a summer bill. In a mild month cooling is likely a smaller part of the bill, so FPL's 60% share and this table would overstate the saving.
Florida thermostat schedule (sourced)
| Situation | Setting | Source |
|---|---|---|
| Home and awake | 78°F, or the warmest you are comfortable at (range 75–78°F) | FPL tips; FPL Ask the Expert |
| Away for the day | About 82°F (range 80–82°F) | FPL tips; FPL Ask the Expert |
| Coming home | Step down about 2°F at a time; do not drop it all at once | FPL Ask the Expert |
| Thermostat fan | AUTO, not ON | FPL Ask the Expert; FSEC |
| Asleep or away (setback) | Back 7–10°F from normal for 8 hours a day: up to 10% a year saved | U.S. DOE |
| House closed for weeks in summer | Not just "set it at 85°F": see the closed-house section below | UF/IFAS; FSEC |
| Indoor humidity | Below 60% RH, ideally 30–50% | EPA |
A programmable or smart thermostat can run this schedule for you. DOE: programmable thermostats bring temperatures back to normal before you wake or return home.
Why fan AUTO matters more in Florida
Your AC dries the house by condensing water on the cold indoor coil. That water drips into the pan and out the drain line, but only while the coil stays cold. When the compressor shuts off and the fan keeps blowing, room air passes over the still-wet coil and picks some of that water back up before it can drain.
- Measured in a Florida house. The Florida Solar Energy Center (FSEC) reports that at a 77°F setpoint, one Florida test home held about 50% relative humidity with the fan on AUTO and 60–65% with the fan on ON, even though it had a two-stage system with a low fan speed during off cycles.
- Measured on a test unit. An earlier FSEC test on a packaged terminal unit found that with 10 minutes of cooling and the fan running through a 10-minute off period, 19% of the water the coil had condensed went back into the room.
- Fan "overrun" does the same thing in a smaller dose. Many air handlers ship set to keep the fan running briefly after the compressor stops. FSEC recommends disabling that delay in hot, humid climates; in one simulation a 90-second overrun raised the hours above 60% humidity by about 80%. Changing it is an air-handler setting, so ask whoever services your system rather than opening the unit.
- Want air moving? FSEC suggests local devices such as ceiling fans or a room air cleaner instead of running the system fan on ON. FPL: ceiling fans counterclockwise in summer, and off when you leave the room, because they cool people, not rooms.
Leaving the house closed for the summer
Seasonal residents and long summer trips are a Florida problem of their own. You do not need the house cool, but you do need it dry. UF/IFAS Extension's "Closing Your Seasonal Home" says to set the AC no higher than 85°F so it still cycles and pulls moisture out, change or wash the filter, clean the condensate line before you go, and have someone check on the house.
FSEC tested this in three Brevard County homes (a concrete block house, a split-level, and a single-wide mobile home), with the goal of keeping humidity below 65% most of the time. What they found:
- 85°F alone often was not enough. It worked fairly well on hot sunny days, but on cooler, cloudy, humid days the AC barely ran, so it barely dried the house. Even 83°F did not reliably control humidity, especially in fall, and in some test periods neither setting made the AC run at all.
- A short early-morning run worked better. A programmable thermostat set to 74°F from 3 to 5 AM, fan on AUTO, worked well in most homes. In a leakier home two hours gave 65–70% humidity, and adding a second run from 10 AM to noon brought the average to 59%.
- It only works if the AC is healthy. FSEC notes this approach assumes the system still blows cold air, and that the thermostat clock keeps its schedule after a power blip. A cheap humidity meter that records high and low readings, checked by whoever looks in on the house, tells you whether your setup is working.
Before you leave: fan on AUTO, interior doors open, filter changed, and the condensate drain flowing. A clogged drain with nobody home can mean a water-damaged ceiling or floor by the time you are back.
Before you turn it down, check these
- Humidity, not just temperature. A cheap humidity meter tells you more than the thermostat number. Above 60% with the AC running normally points at runtime, sizing, or airflow. See AC runs constantly, short cycling, and the dehumidifier pint planner.
- Fan on AUTO. On ON the fan runs nonstop. FPL: if the AC normally cycles off about 30% of the time, ON can add more than 200 extra hours of fan run time a month. FSEC: it also puts water from the coil back in the air.
- Vents open. FPL: closing vents can make the system work harder and use more energy. Closed bedroom doors starve returns. See closed doors & return air.
- Thermostat location. A thermostat in a supply-vent blast or afternoon sun reads wrong and cycles wrong. See thermostat near a supply vent.
- Filter. FPL lists clean filters among its efficiency tips. A wrong-size or too-restrictive filter starves the coil. See the air filter size finder and AC freezing.
- Outdoor unit clear. Florida yards grow fast, and a choked condenser can't shed heat. See outdoor coil & condenser clearance.
What the setting will not fix
Setting problem
House is comfortable at 76°F but the bill is high. Thermostat fan on ON. Away all day at the same setting as evenings. Dropping it to 70°F "to cool faster." These are schedule fixes.
Not a setting problem
Runs all afternoon and never reaches 78°F. Sticky above 60% humidity. Warm air from the vents. Ice on the copper lines. Water at the indoor unit. Turning the thermostat down will not fix any of these. Use the checklists linked above, or call whoever you already trust.
This is a homeowner settings guide, not an energy audit or a repair quote. The per-degree and setback percentages are published rules of thumb from FPL and the U.S. Department of Energy, and the humidity results come from specific FSEC test homes; your home, ducts, and equipment change the real numbers. No form, no shop phone.
Common questions
What temperature should I set my AC to in Florida?
FPL's guidance is 78°F, or the highest temperature you are still comfortable at, while you are home, and about 82°F when you are away. FPL's Ask the Expert pages give a home range of 75°F to 78°F. There is no single right number for every house; pick the warmest setting in that range your household is comfortable with, keep the fan on AUTO, and watch indoor humidity.
How much do I save for each degree I raise the thermostat?
FPL says each degree you raise your thermostat between 75°F and 78°F can save 3% to 5% on your monthly cooling costs, and that cooling makes up approximately 60% of the bill. On a $200 summer bill, going from 75°F to 78°F works out to roughly $10.80 to $18.00 a month. That is a utility rule of thumb, not a guarantee; your home, ducts, and equipment change the result.
Should I turn my AC up when I leave the house in Florida?
Yes. FPL says raising the thermostat while you are away and lowering it when you get home is the more energy-efficient choice, and suggests about 80°F to 82°F when away. The U.S. Department of Energy says you can save as much as 10% a year on heating and cooling by turning the thermostat back 7°F to 10°F for 8 hours a day from its normal setting.
Should the thermostat fan be on AUTO or ON in Florida?
AUTO for most homes. FPL says ON runs the fan nonstop, uses more energy, and adds wear on the fan motor. The Florida Solar Energy Center adds a humidity reason: with the fan running while the compressor is off, water on the wet coil evaporates back into the house. In one Florida home at a 77°F setpoint, indoor humidity was about 50% on AUTO and 60–65% on ON.
What should I set the AC to if I leave my Florida home for the summer?
UF/IFAS Extension says no higher than 85°F so the AC still cycles and removes moisture. Florida Solar Energy Center testing found 85°F, and even 83°F, often failed to control humidity on cloudy, humid days because the AC barely ran. A programmable thermostat running the AC at 74°F from 3 to 5 AM with the fan on AUTO worked better in most test homes; a leakier home needed a second run from 10 AM to noon. Clean the condensate drain and change the filter before you leave.
Will setting the thermostat lower cool my house faster?
No. The U.S. Department of Energy says setting the thermostat colder than normal when you turn on the AC will not cool the home any faster and can lead to overcooling and unnecessary expense. FPL suggests stepping it down about 2°F at a time when you get home instead of dropping it all at once.
What if the house still feels sticky at 78°F?
Check humidity before you chase a lower number. The EPA says to keep indoor relative humidity below 60 percent, ideally between 30 and 50 percent, and that an inexpensive humidity meter can measure it. If it sits above 60% with the AC running normally, make sure the fan is on AUTO, then look at runtime, short cycling, return air, and the filter.
Also here
AC tonnage calculator · SEER2 savings calculator · AC runs constantly · Short cycling · Thermostat near supply vent · Closed doors & return air · Dehumidifier pint planner · Air filter size finder · Florida AC maintenance checklist · Tools hub. Tools and guides in this same set. Nobody's advertising a shop here.
Sources
- FPL, Energy Saving Tips (retrieved Oct 7, 2026): 78 degrees or the highest comfortable temperature while home, 82 degrees away; each degree raised between 75 and 78 degrees can save 3–5% on monthly cooling costs; cooling is approximately 60% of the bill; ceiling fans counterclockwise in summer, off when you leave the room. fpl.com/save/lower-bill/tips.html
- FPL, Ask the Expert: ON or AUTO (retrieved Oct 7, 2026): AUTO runs the fan only while cooling; ON adds more than 200 extra fan hours a month if the AC cycles off about 30% of the time; 75–78°F home, around 82°F away; keep vents open; clean filters. fpl.com/blog/ask-the-expert/ac-settings.html
- FPL, Ask the Expert: How to adjust your A/C before leaving (retrieved Oct 7, 2026): raising the setting while away is more efficient; 80–82°F away; step down about 2°F at a time on return. fpl.com/blog/ask-the-expert/adjust-ac.html
- U.S. Department of Energy, Energy Saver: Programmable Thermostats: as much as 10% a year by turning the thermostat back 7–10°F for 8 hours a day; a colder-than-normal setting will not cool the home faster. The live energy.gov page returned 404 on Oct 7, 2026; text verified from the June 28, 2026 archived copy.
- U.S. EPA, A Brief Guide to Mold, Moisture and Your Home: keep indoor humidity below 60 percent (ideally 30–50 percent); measure with an inexpensive humidity meter. epa.gov/mold/brief-guide-mold-moisture-and-your-home
- Florida Solar Energy Center, FSEC-PF-443-08, AC System Equipment Specification, Installation and Operational Options for Improved Indoor Humidity Control (retrieved Oct 13, 2026): Florida residence at 77°F setpoint, about 50% RH on AUTO vs 60–65% RH with constant fan; disable supply fan overrun in hot/humid climates (90-second overrun raised hours above 60% RH by 80% in simulation); use ceiling fans or room air cleaners for extra circulation. Available in the University of Central Florida STARS repository by report number.
- Florida Solar Energy Center, FSEC-PF-118-87, Another Aspect of Duty Cycling: Effects on Indoor Humidity: 19% of condensed moisture re-evaporated with the fan running through a 10-minute compressor-off period. Available from FSEC publications by report number.
- Florida Solar Energy Center, FSEC-CR-1487-04, Evaluation of the Impact of Vacant Home Space Conditioning Strategies on Summer Relative Humidity, Energy, and Peak Load (Brevard County test homes; site timed out Oct 13, 2026, text confirmed from indexed copies of the report): target RH below 65% most of the time; AC at 85°F or 83°F gave poor humidity control on cloudy, humid days; 74°F from 3–5 AM with fan AUTO worked in most homes; a leakier home needed a second run 10 AM–noon (average 59% RH). Available from FSEC publications by report number.
- UF/IFAS Extension, HE887 Closing Your Seasonal Home (retrieved Oct 13, 2026): set the AC no higher than 85°F; change or wash the filter; clean the condensate line; have someone check on the home. ask.ifas.ufl.edu/publication/HE887