How to set a thermostat during extreme heat?

Author: Myrtice Abshire  |  Last update: Wednesday, September 3, 2025

Rochester Electric and Gas recommends setting your thermostat at 78 degrees or higher, as each degree above 75 degrees saves 3% of energy on cooling. A higher internal temperature actually slows heat flowing into your living space, so it saves additional money on air conditioning.

What should I set my thermostat to in extreme heat?

The Best AC Temperature When It's 100 Degrees
  • Comfort: Some people may prefer a slightly cooler thermostat setting in the summer, such as 75-77 degrees, especially during extremely hot weather. ...
  • Energy Efficiency: Setting the thermostat to 78-80 degrees can help save energy and reduce utility bills.

How cool should my house be if it's 100 outside?

When temperatures exceed 100 degrees Fahrenheit outside, setting your air conditioning (AC) to around 75-78 degrees Fahrenheit is generally considered efficient. Here are some reasons for this recommendation:

What should I set my AC to in extreme heat?

The answer is to set it as high as you can to still maintain a level of comfort. The Department of Energy (DOE) recommends a setting of 78 degrees when you're home and 80 degrees when you're away. When the outside temperature is in the high 90s or more than 100 degrees, your cooling system has to work hard.

Is 72 too high for a thermostat in winter?

68 to 72 degrees is a temperature range that is not too warm or cool, and is sufficient enough to warm up the home just enough so that everyone is comfortable regardless of the type of clothing they have on.

Thermostat Secrets And Other Tips To Reduce Your Utility Bills

Is 72 a good temperature for air conditioning at night?

WHAT SHOULD I SET MY AC TO AT NIGHT? According to the Cleveland Clinic, the recommended thermostat setting for nighttime is between 60°F and 67°F. 3 Setting your AC within this range can help maintain a comfortable sleeping environment.

Is 82 too high for AC?

While ENERGY STAR suggests 82 degrees, that may be too uncomfortable for most families. Most people sleep better when their sleeping area is chilly, so that's why the National Sleep Foundation advises 60–67 degrees.

Is 78 too hot for a house?

Quick answer: The ideal house temperature is room temperature, which ranges from 68 to 78 degrees F, though this may vary from season to season. In winter, the average room temperature is generally 62 to 68 degrees, whereas in the summer, the average temperature is 72 to 78 degrees.

Does keeping the AC at 72 save money?

Best AC Temperature Settings While You Are Home

As you consider the most comfortable room temperature for your lifestyle and family, keep in mind that for each degree that you set your thermostat above 72 degrees, you can save up to 3% on your energy bill.

Is 68 too low for AC?

During a heatwave, we recommend that you don't lower the AC's setting below 68°F. This is already quite chilly for most people, and many would consider it too cold. An air conditioner set this low risk of its coil freezing—and that's bad news because it indicates that the air conditioner is overworked.

How cool should my house be if it's 110 outside in summer?

Just because the outdoor temperature is above 100, the Ideal temperature to set your AC unit to doesn't change — it's 78 degrees. Higher temperatures in the home are to be expected when the weather is hotter than usual, but your thermostat can still be set the same as if it were a lower temperature outside.

How long should it take to cool a house from 90 to 72?

Cooling a house from 90 degrees to 72 degrees typically takes about 2 to 4 hours, depending on various factors.

What should the AC setting be based on outside temperature?

Most air conditioning systems can only handle a 20-degree difference between the outside and inside air temperatures. If it's 80 degrees outside and your thermostat is set to 70, your unit should have no problem.

What temperature to keep a house at during a heat wave?

Finding a comfortable, middle-of-the-road setting between the inside temperature of your house and the outdoors will help you get accustomed to warmer weather. Somewhere around 78 degrees is a reasonable temperature to save energy and meet your needs when you're at home.

Is it better to keep your AC at a constant temperature?

Instead of choosing a constant temperature year-round, it's better to keep your house a constant temperature on a seasonal basis. Keeping your home at a higher temperature during the warmer months will mean your air conditioner doesn't have to work as hard.

Is it cheaper to leave your thermostat at one temperature?

When it comes to energy efficiency and cost savings, the debate about thermostat settings can be complex. On the one hand, keeping a constant temperature can be more energy-efficient in some cases because your HVAC system doesn't have to work as hard switching between temperatures.

Why not set the thermostat at 72?

Setting the thermostat below 72 degrees while using an air conditioner can cause the unit to work harder than necessary, leading to higher energy bills and potential damage to the appliance.

What is the cheapest temperature to keep AC on?

Finding the right AC temperature for your electricity bill is a balancing act. By setting it around 78°F and considering external factors, you can enjoy comfort and save on energy costs simultaneously. Remember, small adjustments can lead to significant savings over time.

Should my thermostat be on run or hold?

The best way to save money is by combining both. The “run” feature lets you preset the temperature when you're not home to prevent wasting money on cooling or heating an empty home. Meanwhile, the “hold” button lets you change the room's temperature without changing your energy-saving, preset schedule.

Can you sleep in 78 degrees?

“Anything under 68 degrees overall is ideal for sleep. If you get too hot in the middle of the night, reduce layers of clothing or sheets, turn on fans, or drink a little cold water.”

What happens if I put my AC on 80 degrees?

If you set your thermostat in the 80s, the air conditioner won't run enough to effectively dehumidify your home's air. Here in the Tennessee Valley, we have extremely humid weather in the summertime. If your thermostat is set at 80+ degrees, then the humidity inside of your home can easily get up above 70%.

Does setting your thermostat at 78 degrees really help?

The community-owned electric utility advises customers to set their thermostats to at least 78 degrees during the summer and 68 degrees during the winter. “You'll save around 5% to 10% on cooling costs for every two degrees you raise the temperature,” SMUD wrote on its site. Pacific Gas and Electric has similar advice.

What should I set my AC to on a hot day?

Summer Air Conditioner Settings

In the summer, experts say the thermostat for your air conditioner should be set to at least 78°F during the day when people are at home.

Why is my AC set to 72 but reads 78?

Clean the Thermostat

Sometimes, when the room temperature doesn't match the thermostat setting, the problem could be dirt buildup on its interior parts. A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings.

What is the hottest you should let your house get?

The Safest Temperature for Humans and Pets

Heat can be dangerous, so you don't want to let your home get too hot. The absolute highest you should set your thermostat is around 82 degrees Fahrenheit.

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