The dog’s sprawled belly-up on the cool tile, the box fan is doing its best impression of a jet engine and you’re eyeing the thermostat like it personally betrayed you. Because every time you touch it—up, down, doesn’t matter—it feels like you’re playing a losing game between comfort and cost.

You’re not alone. Across the country, energy bills skyrocket the moment the temperature does. You try to be smart: Raise it a few degrees when you leave the house, turn it down when you get home, tell yourself ceiling fans count as strategy. Still, the numbers on your utility bill keep climbing. So what gives? It actually may boil down to the time of day you adjust your thermostat.

Read on to find out how that one little change can make a big difference—both in how cool your house stays and how much you save on your energy bills this summer.

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What’s the ideal temperature for your home in the summer?

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The U.S. Department of Energy recommends setting your thermostat to 78 degrees Fahrenheit when you’re home during the warmer months. And yes, that number tends to spark debate. But when paired with fans, closed blinds and good airflow, most people find it more comfortable than they expect.

“Try inching your thermostat up one degree at a time until you find your threshold,” says Tom Dart, a product manager at Copeland thermostats. “You don’t need to jump straight to 78 degrees Fahrenheit, but even going from 72 to 74 can make a dent in your energy use.”

The savings really kick in, though, when you start thinking about when to adjust the thermostat.

What’s the best time of day to adjust your thermostat in summer?

Here’s where many people miss the mark: adjusting their thermostat based on daily habits, not energy pricing. “Time-of-use pricing means electricity is more expensive during peak demand hours, usually from 2 p.m. to 7 p.m.,” Dart explains. “If your system is cooling hard during that window, it’s costing you more.”

So instead of letting your AC battle the mid-afternoon heat, cool your home down earlier in the day, ideally mid- to late morning, when demand (and prices) are lower. Then, raise the thermostat several degrees before peak hours begin, letting your home “coast” through the hottest part of the day. Think of it like preloading comfort.

Why does this timing make such a difference?

It’s not just about cheaper rates. It’s also about giving your cooling system a fighting chance. “If your AC waits until 3 p.m. or 4 p.m. to start cooling, it’s up against the hottest outdoor temperatures and a house that’s already warmed up,” says Dart. “That means the unit has to work much harder to cool things down quickly.”

That intense, sustained strain not only uses more energy but also wears down your system over time. Precooling in the morning lets you get ahead of the heat, using less energy to maintain a comfortable temperature—and avoiding that last-minute, high-powered catch-up effort.

How much can you potentially save?

According to Energy Star, homeowners who follow a smart thermostat schedule and adopt energy-efficient cooling habits can save up to 23% on their HVAC-related energy costs. Let’s say your typical summer energy bill is around $200 a month, and half of that (about $100) is from air conditioning. A 23% savings on the cooling portion would knock $23 off your bill each month. Of course, that can vary depending on the size of your home … and just how frigid your family members like to keep things.

One thing to keep in mind: To reap those kinds of savings, you’ll likely also have to incorporate other best practices. Don’t worry, they’re small. We’re talking about things like adjusting the thermostat during sleep or away hours, avoiding heat-generating appliances during the day and using ceiling fans to extend your comfort range.

Can your utility company help you save too?

Yes—and if you’ve never looked into your utility’s rebate or “demand response” programs, now is the time. Many energy providers offer summer savings programs, where you can opt in to allow minor thermostat adjustments during peak hours when the grid is under the most stress from people arriving home and cranking the AC.

Here’s how it works: Once enrolled, your utility company may dial back your cooling slightly during a peak-demand event (you’ll get a heads-up on your thermostat or app). You can always opt out of a particular event if needed—you’re still in control—but participating can earn you rebates or annual credits on your bill.

“It’s a simple way to help the grid and your wallet,” says Dart. “Even small reductions during those high-stress windows can add up system-wide.”

How else can you save on cooling costs in the summer?

Timing and thermostat settings are huge, but they’re just the start. Here’s what else you can do:

  • Close blinds or curtains by late morning to block solar heat gain.
  • Use ceiling fans to make warmer temperatures feel cooler. (Just remember to set blades to spin counterclockwise to help create a downdraft, which creates a direct, cooling breeze.)
  • Don’t use the oven and dryer during peak hours. You can also batch cook in the cooler parts of the day.
  • Invest in a programmable or smart thermostat, which can automate your ideal schedule and even adjust itself based on the room in your home that you want to focus on cooling.

In the end, beating the heat isn’t just about what temp you set—it’s about knowing when to make your move. And in this game, timing really is money.

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About the expert

  • Tom Dart is a product manager at Copeland thermostats. His specialty is Sensi smart cooling technologies.

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