Best Florida summer air conditioner temperature? It depends

Jan 03, 2024

Every summer — and spring and fall, in Florida — we face the eternal question: what temperature should I set my thermostat on?

Florida and the world have been suffering through a sweltering summer this year that has broken many heat records. We saw the hottest July since people have been keeping track and the second-hottest month ever, with multiple cities breaking their own records including Pensacola, Jacksonville, Tampa, Sarasota, Vero Beach, Fort Myers, Naples, Miami and Key West, based on their monthly average temperatures.

The heat index, also called the "feels like" or "real feel" temperature which uses temperatures and humidity levels to tell you what it's actually going to feel like out there, has been hitting over 115 in the shade for weeks, triggering daily excessive heat warnings from the National Weather Service. And it's likely going to stay hot through August and into September, according to the Farmer's Almanac.

It's hot out, is what we're saying.

So what temperature should you set your air conditioner on? Short answer: it depends.

There isn't a magic number that everyone should use. It's a decision you make based on:

The first and last ones are key. If you can afford it, run your a/c as low as you want. Just be prepared for considerably higher bills and likely more air conditioner maintenance and repairs.

Katarina Alvarez, a senior communications strategist for Florida Power & Light, said a one-degree increase in thermostats could save between 3-5% on cooling costs. The less your a/c has to work, the lower your bill.

So set your thermostat to the highest temperature that you can remain comfortable in and can afford, and look for other ways to cool off your place.

For a long time, 78 degrees has been the number everyone drops in their "stay cool" guides. Which is fine for some people, and for lizards.

When the media and electric utility companies promote 78 degrees they often refer to ENERGY STAR, a program run by the Environmental Protection Agency and the U.S. Department of Energy that has become synonymous with energy-efficient appliances. But ENERGY STAR doesn't recommend any specific temperature.

“ENERGY STAR does not assert that any particular temperature setting is good for households,” the EPA said in an email to The Palm Beach Post.

In the Florida summer, probably not a good idea unless you just like the heat.

Temperatures don't drop that much in the Sunshine State overnight and letting the place heat up means your a/c will have to start from scratch in the morning. It also means letting in a lot of moist, hot air that will get absorbed by the carpeting and furniture upholstery, which means an uncomfortable house and the increased possibility of mildew.

The work your a/c will have to do to bring the temp back down to liveable when you get home from work may not be worth what you save by turning it off.

Air conditioning also helps reduce humidity in your house, and that helps keep mold and mildew in check. There are also your pets to consider. Your dogs and cats don't like the heat any more than you do, and they have fewer ways to cool off.

When you're out of the house for an extended amount of time, FPL recommends setting your thermostat to 85 degrees with the fan on "auto."

Older adults are more prone to heat stress, according to the Centers for Disease Control. They don't adjust as well to temperature changes, they're more likely to have a chronic medical condition that changes their normal responses to heat, and they're more likely to take prescription medicines that affect the body's ability to control its temperature.

Older people also are more prone to Alzheimer's disease and other dementia-related illnesses, and scorching heat can be even more dangerous for individuals who may not notice that they're overheating, may not understand what it means, may have impaired judgment, or may not be able to tell anyone about it.

"Summer can be extremely dangerous for those with Alzheimer's in Florida," Julie Shatzer, Vice President of Programs for the Florida chapters of the Alzheimer's Association, said in an email. "Symptoms of overheating can be difficult to detect in those with Alzheimer's and other dementia since they can be similar."

Turning off the a/c isn't much of an option when overnight temperatures stay in the high 70s and it doesn't save you much money since your a/c will have to work that much harder in the morning to catch up. But there are plenty of ways to give your air conditioner less to do.

ENERGY STAR recommends once a year, in the spring, but Floridians might want to go twice, especially if you live near the coast.

Your a/c needs to be repaired if it stops working (obviously), makes loud noises while running, or can't keep your house cooled to at least 78 degrees. But it might need to be replaced if it's over 10-15 years old, your energy bills have skyrocketed and you keep having to get it fixed

Older units have other issues, such as increasingly scarce parts or outdated coolant. The U.S. ceased production of Freon in 2020 and older units used R-22 Freon, which is getting tougher to find. And newer systems are more energy efficient.