Hot Car Fatalities Are a Year-Round Threat to Children and Pets

CR's testing shows it doesn't take scorching temps for hot cars to pose safety risks

By Emily A. Thomas, PhD
Associate Director, Auto Safety

Updated by Jessica D’Argenio Waller, MS, CNS, LDN

Updated April 30, 2025

Sunlight shining on back window of parked SUV — Heatstroke is the leading cause of death in vehicles (excluding crashes) for those 14 and younger.

Heatstroke can be a four-season threat in some parts of the country. About 39 children die each year from vehicular heatstroke, according to Kids and Car Safety and NoHeatstroke.org. Heatstroke is the leading cause of death in vehicles (excluding crashes) for those 14 and younger.

There were 40 hot car deaths in 2024, according to Kids and Car Safety. In most cases, the children were unknowingly left behind in the vehicle. While it may be difficult to believe that you or your friends and family could face such a sad event, it’s important to remember that research shows these tragedies can happen to anyone.

Historically, about a quarter of hot car deaths have been the result of the child gaining access to the car on their own, according to NoHeatstroke.org. As temperatures rise and more kids are playing outside, parents and caregivers need to be extra mindful of their children’s whereabouts. And they need to keep vehicles locked in the garage or driveway, and the keys out of children’s reach. Even if you don’t have children, it’s important to take those precautions to protect neighboring families.

If your child is missing, always remember to first check your pool, if you have one, and then your vehicle, including the trunk.

It’s never safe to leave a child unattended in a vehicle. Even with the windows cracked or the vehicle parked in the shade, the car’s interior temperatures can reach dangerous levels in a short period of time.

And don’t be fooled by the thermometer: On days with mild temperatures, the heat inside a closed vehicle can reach dangerous levels within an hour, posing major health risks to small children or pets left inside, Consumer Reports says.

CR’s testing found that even when it was 61° F outside, the temperature inside a closed car reached more than 105° F in just 1 hour, an extremely dangerous and potentially fatal level for a child.

The CR test results help dispel the myth that hot car deaths or heatstroke happen only on blisteringly hot days in the dead of summer.

And the idea that your car’s color can significantly mitigate the heat inside the vehicle is also largely a myth, based on CR’s testing.

“Children should never be left unattended in a car for even a short period of time,” says Jennifer Stockburger, director of operations at CR’s Auto Test Center. “Even when it’s not that hot outside, our test results show how quickly temperatures inside the car escalate, regardless of whether your car is light or dark.”

And research shows that drivers shouldn’t rely on external shade to cool the cabin, either. Researchers at Arizona State University and the University of California at San Diego School of Medicine evaluated cabin air temperature and surface temperatures in identical vehicles placed in the shade and the sun. Their study estimates that even in a shaded vehicle, a 2-year-old child’s core temperature could reach a dangerous—and potentially deadly—104° F in a little less than 2 hours.

The danger from high temperatures is particularly acute for young children because their bodies heat up three to five times faster than adult bodies, according to the American Academy of Pediatrics (AAP).

That’s because young children, especially babies, lack the ability to efficiently regulate their body temperature. Children dehydrate more quickly than adults.

Many automakers have integrated detection-and-alert technology into vehicles to remind parents or guardians that they might be leaving a child or pet behind.

CR's Test Findings

Consumer Reports conducted several temperature tests inside closed vehicles at CR’s Auto Test Track in Colchester, Conn., to better understand how rapidly the rising cabin temperatures can become unsafe. The experiments were conducted with precision instruments.

On a June day when it averaged 61° F outside during the first hour of testing, the inside of a parked car reached more than 105° F.

On a July day when it averaged 78° F outside during a 1-hour test period, the inside of a lighter-colored sedan reached more than 104° F. And during the same 1-hour test period, the inside of a dark-colored sedan reached more than 109° F.

CR reported the readings at the end of an hour. But interior temperatures continued to rise as more time passed.

Hot car testing 2024 at ATC — A BMW iX and a Honda HR-V sit in the sun as part of our hot car testing.

Exploring more variables, we recently performed similar tests on seven vehicles, looking at the impact of interior color and moonroof with and without a retractable shade. We found similar results: Temperatures elevated to dangerous levels just as quickly.

“Our tests repeatedly show that a closed car parked on a warm—not even hot—day can see its interior temperature rise to dangerous levels within an hour,” Stockburger says. “There is no magic combination that avoids the potential danger to children or pets left in a car. The simple takeaway: Leave no one behind. Ever.”

The National Highway Traffic Safety Administration mirrors our own test findings. That government safety agency has warned that on a 60° F day—something akin to spring weather—the temperature inside a vehicle can reach a dangerous 110° F over the course of several hours.

The threshold for heatstroke in children is when the internal body temperature reaches about 104° F. And a child is at serious risk of death if their internal body temperature reaches 107° F, according to medical experts.

Heatstroke risk is a year-round threat in some regions with mild winters, including the South and Southwest.

Car Color and Temperature

The chart below demonstrates the rise in vehicle cabin temperature when CR tested two sedans on a July day.

Why Cars Heat Up

Closed cars get hot quickly because sunlight heats up inside elements, including the dash, upholstery, and steering wheel, according to NoHeatstroke.org. Those elements radiate their heat into the air, increasing the ambient temperature inside the car.

Why don’t cracked windows help enough? Partly opened windows allow some heat to escape, says Jake Fisher, senior director of auto testing at Consumer Reports, but as long as the heat source (the sun) continues to beat down and heat up the inside car elements, the temperature can stay dangerously high.

CR's Take

Consumer Reports believes that automakers should integrate features that can detect children in the vehicle cabin and trigger an alert, and get the technology into as many models as they can, as soon as they can. Aftermarket products can fall short because they still depend on adults recognizing the risk and taking some sort of action.

“Automakers have demonstrated that it’s feasible to build integrated, protective systems into their vehicles,” says William Wallace, CR’s associate director of safety policy. “As these technologies advance, CR will evaluate them and advocate for strong standards to ensure that all new car buyers—not just those who pay for a premium upgrade package—get an effective detection-and-alert system they can rely on.”

The AAP also endorses the integrated approach.

“Having something that is in the vehicle that is a default, that you would have to opt out of, is the right way to go about it,” says Elizabeth Murray, DO, an AAP spokesperson. “These are not people making malicious decisions to try to hurt their children. These are terrible accidents that are happening, so if we can make it default to take any human error out of it, then that is the right decision.”

Emily A. Thomas, PhD

Emily A. Thomas is the associate director of auto safety at the Consumer Reports Auto Test Center, leading the child car seat and rear-seat safety programs. She joined CR in 2015 after earning her doctorate in pediatric injury biomechanics from Drexel University and Children’s Hospital of Philadelphia, focusing on the biomechanical differences between kids and adults in far-side low-speed crashes. Involved in automotive safety since 2008, Emily has been a certified child passenger safety technician (CPST) since 2015.