Why a Fan Can’t Always Cool You Down, and Other Unexpected Challenges in Heat Waves

People across the United States are in for another scorcher of a summer, according to an outlook from the National Oceanic and Atmospheric Administration. 

The agency predicts “hotter-than-average” temperatures, a trend that is becoming increasingly common as climate change worsens. These high temperatures can be deadly; research shows that heat-related deaths have more than doubled over the past 24 years. With the air-conditioning market at an all-time high, it’s clear that individuals are scrambling for ways to stay cool. Meanwhile, cities and states are implementing new strategies and technological solutions to protect communities in a more holistic way, from tree-planting initiatives to cooling centers. 

However, experts stress that most of these heat-combating strategies have limitations—and some can even make things hotter. 

A Fan’s Threshold: Medical experts have dubbed heat a “silent killer” because many people don’t realize they are in trouble until it’s too late. That’s because the symptoms can start out pretty slowly—heavy sweating, headaches or nausea—but worsen rapidly to a rash, seizure or even stroke. Heat-related deaths are notoriously difficult to track and often marked as something else on a death certificate, but research suggests that extreme heat has caused more deaths in an average year than all other weather disasters combined. 

The best way to prevent heat stress is obvious: cool down. But the best way to do that can be a little more complicated. 

Officials agree that the single most effective method for staying safe during a heat wave is to secure access to an air-conditioned space. However, A/C inequity cuts across the U.S.: More than 35 million people report living in a household without an air conditioner, according to one estimate. This lack of access is most common in minority and low-income communities, laying bare an environmental justice issue that is only expected to get worse by 2050, according to a recent study. 

To help address this, some municipalities in Texas and Louisiana have offered free electric box fans to residents in recent years. But when temperatures pass a certain threshold, these fans alone do almost nothing to help beat the heat, according to a growing body of research. A 2024 review study found that electric fan use in air temperatures more than 95 degrees Fahrenheit “should not be expected to provide meaningful bodily cooling during hot weather and heatwaves.”

Typically, the fast air moving from fans displaces the warmer air that comes in contact with our skin, which makes it easier for sweat to evaporate and eliminate body heat. However, this research finds that when air temperatures pass 95 degrees, fans can exacerbate the transfer of heat to the body from the environment by blowing hot air on your skin. 

“When you’re sitting in front of a fan, it makes you feel cool. But just because you feel cool doesn’t mean that it’s exactly reducing the burden that your body faces,” study co-author Glen Kenny told me. He’s a physiology professor at the University of Ottawa who studies heat. 

Kenny’s lab has conducted a range of experiments on how a person’s body exchanges heat with their environment. His team ran a separate experimental trial on older adults to test how electric fans affect heat stress, which echoed the findings of his 2024 study. 

There is some debate over what the exact temperature limit is for fans’ effectiveness, particularly when it’s also humid outside. Experts agree that there should be more research on where these products fit into the toolbox for heat adaptation before government guidance is issued, Science reports. 

Individuals over 65 are more prone to heat-related problems, largely because their glands don’t release as much sweat. But a number of other factors can also influence how your body processes heat, from the medication you take to your weight. Kenny himself was sick on the day we spoke, which he said can hinder his body’s ability to stay cool. 

“If I go and expose myself to heat—and I exercise all the time—I would be highly vulnerable, because I’ve lost that capacity. It compromises my ability to potentially thermoregulate,” he said. “If you’re an older person, sleep deprived, or you’re suffering from depression, all these factors play into your capacity.” 

How frequently you are exposed to heat can also play a part. If someone is consistently exposed to high temperatures or humidity, their body can acclimate to those conditions to an extent. That means a person from the steadily scorching city of Phoenix may have a higher heat tolerance than someone from Juneau, Alaska, a phenomenon I wrote about last summer. 

Context Is Key: As temperatures inch up, cities in particularly hot regions are implementing an array of strategies to help reduce heat in the area. My colleague Wyatt Myskow is based in Phoenix and frequently writes about the city’s heat mitigation plan, which is widely considered one of the best in the country. 

The local government and universities in the area have partnered to expand shade through tree-planting initiatives, installed pavements that help reflect sunlight and opened several cooling centers so people without access to air conditioning have somewhere to go when temperatures rise above 95 degrees, which is common during Phoenix summers.  

But all of these efforts can have trade-offs depending on their implementation, experts say. For example, reflective materials on pavement can help counteract the solar radiation that would have otherwise been absorbed by dark roads, but this rebounded radiation can warm buildings if they are too close by. 

Even longstanding tools like weather-protecting shelters at bus stops can have a detrimental impact during heat waves in certain circumstances, according to a study published in March. 

Researchers tested temperatures under a variety of differently designed bus shelters in Houston, and determined that most of them significantly reduced wet bulb globe temperatures—a measure of heat stress in direct sunlight, which incorporates factors like the air temperature, wind speed and humidity. But they also discovered that the shelters can’t provide shade from the sun at certain times of day, turning them into metal heat traps. Tree shade was more effective at cooling than any of the designs. 

Last year, the city of Houston launched an initiative to build thousands more bus shelters with similar designs as those the research focused on. However, lead study author Kevin Lanza told me that the city is currently working on designs that will improve the ventilation at these stops. 

I asked Lanza about other structures like cooling centers, which he said can be incredibly effective at preventing heat stress—but only if they are built with people in mind. Reports show that many of these buildings in Florida, Arizona and other states sit relatively empty during a heat wave for a variety of reasons, such as a lack of transit to get there or simply a lack of things to do once you are there. 

“We need to incorporate behavioral sciences in the equation of developing cooling centers as a heat intervention,” Lanza said. He’s an assistant professor of environmental and occupational health sciences at the University of Texas Health Science Center at Houston. “I love the idea. I just think that it’s a bit underbaked and underwhelming if we don’t think about people’s behaviors and how they access those spaces.” 

All of that means that protecting lives in a heat wave takes more planning than we might realize.

“There’s not one singular solution that works for all contexts,” he said. “There’s going to be pros and cons of everything.”

More Top Climate News

The Trump administration defunded NOAA’s Center for Heat Resilient Communities, an effort designed to help cities understand how heat moves through their area and how best to mitigate it, Matt Simon reports for Grist. This cut directly affected an ongoing project in Laredo, Texas, to better understand the “urban heat island effect,” a phenomenon in which cities experience warmer temperatures due to the density and types of materials they are built with. Now, researchers who had been gathering data for the project are working on their own time to find new ways to help people in the area apply it. 

Last year, four hydroelectric dams were removed from the Klamath River in Oregon, which experts say will help revive struggling salmon populations. In another environmental win for the region, a 15,000-acre section of the Klamath watershed is now being returned to the Yurok tribe, marking the largest land-back conservation deal in California history, Justin Catanoso reports for Mongabay. 

Though the area first belonged to the Yurok people, Congress passed the Dawes Act in 1887 to enable the U.S. government to strip tribes of their land and waterways. Eventually, the watershed was bought by a logging company, which more recently agreed to sell it for around $56 million. After working and fundraising with the nonprofit Western Rivers Conservancy for the past two decades, the tribe was finally able to secure its land. In recent years, more than 32,000 acres were returned to the Yurok people. 

“There were times over the past 20 years when we weren’t sure this would happen,” Joseph James, the Yurok chair, told Mongabay. “But we never gave up hope. We took a stance and said, ‘We love our river. We love our fish. We love our natural resources. We love our culture. And we’re not shy about showing it.’ That’s what Blue Creek means to us. That’s who we are.”

A new study finds that dehorning rhinos at game reserves in Kruger National Park and other game reserves in northern South Africa and Mozambique has led to a drastic reduction in poaching, Gerald Imray reports for The Associated Press. This technique requires officials to sedate rhinos and cut off their horns using a chainsaw, which may sound gruesome, but some conservation groups say it is the most effective way to prevent them from being killed. Despite its survival success, dehorning efforts remain controversial, as many experts point out that rhinos use their horns to defend themselves and their territory, so we don’t yet understand the full impacts of this method. If the strategy is done right, rhino horns grow back within about 18 months (kind of like fingernails, as Rachel Nuwer puts it in The New York Times).