A dog in a car with the window down

Debarking Pet Myths: Cracking windows open is enough

Welcome to “Debarking Pet Myths,” a monthly series dedicated to addressing common myths, misconceptions and old wives’ tales about dogs and cats.

Every spring and summer, pet owners across the country are warned about the dangers of leaving their pets alone in parked cars. And every year, hundreds of pets become seriously ill or die from heat exhaustion or heatstroke. Sadly, their owners didn’t appreciate how dangerous this month’s myth can be:

Cracking the car windows open is enough to keep my pet safe during hot weather.

The reality? Studies show that leaving car windows partially open has minimal benefit — it’s not enough to prevent the temperature inside a car from quickly rising to deadly levels. Even on a relatively mild day, the interior temperature of a vehicle can become dangerous in a matter of minutes.

A study conducted by researchers at Stanford University and San Francisco State University found that inside a dark-colored car parked outside in temperatures ranging from 72 to 96 degrees Fahrenheit, the temperature climbed as time passed. We’d expect that to happen, right?

But what we might not realize is how quickly a car’s interior can heat. Researchers found the majority of the temperature increase occurs within the first 15 to 30 minutes, and the maximum temperature was reached at about 60 minutes. On average, the final temperature inside the car was 41 degrees higher than the starting ambient temperature. Cracking the windows open about an inch and a half didn’t slow the heating or decrease the maximum temperature reached inside the car.

A study performed by the Louisiana Office of Public Health compared a dark-blue sedan and a light-gray minivan parked on a hot (93 degrees Fahrenheit), partly cloudy day. The temperature inside exceeded 125 degrees Fahrenheit within 20 minutes. It also found that opening the front windows of the minivan 1.5 inches had very little effect on the temperature inside.

Ernie Ward, DVM, a veterinarian in Calabash, North Carolina, experienced for himself what it’s like to sit in a parked vehicle on a summer day. If you haven’t already seen his video, you can watch it here. (Spoiler alert: The interior temperature of his SUV hits 117 degrees Fahrenheit in about 30 minutes, even with all four windows cracked open.)

Protecting pets from “hot cars” through legislation

Veterinary associations and animal advocacy groups estimate thousands of pets die every summer as a result of being left inside a hot car. To help protect our furry friends, 24 states now have “dog/pet hot car laws,” according to the Michigan State University College of Law Animal Legal and Historical Center. Some of these laws not only protect the pet but also protect those rescuers and first responders from being sued or charged with a criminal offense under certain conditions. Some communities also have laws governing pets in parked vehicles. Even without local or state laws, leaving a pet alone in a car during hot weather could result in animal cruelty charges.

Heat-related health issues and deaths are preventable with a little knowledge, planning and precaution. When the thermometer’s mercury soars, the best way to help keep your pet safe is to leave them at home, where air conditioning, fans and shade offer a retreat from the heat.


Debarking Cracking car window enough Totally False graphic

The information in this blog has been developed with our veterinarian and is designed to help educate pet parents. If you have questions or concerns about your pet's health or nutrition, please talk with your veterinarian.


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