What Temperature Should You Set Your AC in a Texas Summer?
Last updated: October 18, 2026 · 5 min read
It is the number every Texas household quietly argues over each July. Set the thermostat too high and the house feels like a sauna; set it too low and the bill stings. The good news is that there is a well-worn guideline to anchor the debate, and a few simple tricks that let you sit comfortably a couple of degrees warmer than you might think.
The short answer
The U.S. Department of Energy commonly suggests about 78°F when you are home in summer, and higher when you are asleep or away. The key rule: every degree cooler you hold the thermostat adds roughly 3-8% to your cooling energy, so going from 78 down to 72 can raise costs noticeably. Fans, closed blinds, and a smart thermostat let you stay comfortable at a higher setpoint. Think of 78 as a starting point, not a mandate.
Where the 78°F Number Comes From
The 78-degree figure is the Department of Energy's long-standing suggestion for a summer setpoint when you are home and awake, with the recommendation to let it climb higher during sleep and away hours. It is not a Texas-specific law of physics — it is a balance point between staying comfortable and not running the compressor any more than you have to. The closer you hold your indoor temperature to the sweltering air outside, the less heat leaks in and the less work the AC does. That is the whole logic behind aiming higher rather than lower.
Why Each Degree Costs More Than You Would Think
Here is the part that changes how people set the dial. As a rough rule of thumb, every degree cooler you hold the thermostat adds somewhere around 3 to 8 percent to your cooling energy use. That is because a lower setpoint means the system runs longer and cycles more often to hold the line against the Texas heat. Drop from 78 to 72 and you are stacking six of those increments on top of each other — which is why a "just a little cooler" habit can quietly raise your summer cooling costs by a meaningful chunk. Since cooling can be 40 to 60 percent of a summer bill, a few degrees is real money over June, July, and August.
Every one of those extra kilowatt-hours is billed at your effective rate, so the setpoint and the plan work together: a warmer setting cuts the kilowatt-hours, and a cheaper rate cuts what each one costs.
How to Stay Comfortable at a Higher Setpoint
The trick to living happily at 78 is to make 78 feel like 75. Ceiling and floor fans are the workhorses here — a light breeze moving across your skin makes a room feel several degrees cooler than the thermostat reads, for a tiny fraction of the AC's energy. Closing blinds and curtains on sun-facing windows during the afternoon keeps radiant heat from baking the house, so the system holds your setpoint with fewer run hours. And a smart thermostat quietly eases the temperature up when you are asleep or out and brings it back before you notice, capturing the savings without a fight. Humidity plays a part too: drier air feels cooler, so a well-sealed home that keeps the muggy Texas outdoor air out stays comfortable at a higher number than a damp one.
Fans cool people, not rooms
A ceiling fan makes you feel cooler through moving air; it does not actually lower the room's temperature. So running one in an empty room saves nothing — the motor just adds a little heat and cost. Turn fans off when you leave, and let them earn their keep only where someone is sitting.
Pick a Number You Can Actually Live With
Be honest with yourself about comfort. 78 is a guideline, not a rule, and a house that is miserable to be in is not a win no matter what it saves. If you and your family are happy at 76, hold 76 and use fans and shade to keep it cheap. If the bedroom needs to be cooler to sleep, cool the bedroom at night rather than chilling the whole house. The goal is to find the highest setting you can genuinely enjoy, then let fans and closed blinds buy back a couple of degrees of felt comfort for almost nothing. For the related question of whether to ease off entirely while you are out, see our guide on whether to leave the AC on or turn it off.
Make every degree cost less ⚡
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What temperature should I set my AC in a Texas summer?
The U.S. Department of Energy commonly suggests about 78 degrees Fahrenheit when you are home and awake in summer, and setting it higher when you are asleep or away. That is a guideline aimed at balancing comfort and cost, not a hard rule. Plenty of Texans settle a degree or two either side of it and use fans and shade to make a warmer setpoint feel fine.
How much does each degree cooler cost?
As a rough rule of thumb, every degree cooler you hold the thermostat adds somewhere around 3 to 8 percent to your cooling energy use, because the system runs longer to hold the lower temperature. So dropping from 78 to 72 does not just cost a little more — it can raise cooling costs noticeably over a full Texas summer. The exact figure depends on your home, but the direction is always the same.
Is 72 degrees too low for the AC?
It is not unsafe, but in a Texas summer it is an expensive habit. Holding 72 instead of 78 means the compressor runs many more hours across the season, and at roughly 3 to 8 percent more energy per degree, that gap adds up. If 72 is what it takes to sleep, try it only overnight, or use fans to feel a few degrees cooler at a higher setpoint before you commit to running the AC that hard all day.
What should I set the AC to when I'm not home?
When the house is empty for hours, let the temperature drift up — the Department of Energy suggests a setback of several degrees above your comfort setting. A programmable or smart thermostat can hold, say, the mid-80s while you are out and cool the house back down shortly before you return, so you are not paying to keep an empty house cold all afternoon.