Quotes by experts

“Children have died in cars with the temperature as low as 63 degrees. Basically the car becomes a greenhouse. At 70 degrees on a sunny day, after a half hour, the temperature inside a car is 104 degrees. After an hour, it can reach 113 degrees.”

– Jan Null, adjunct professor at San Francisco State University

“When temperatures outside range from 80 degrees to 100 degrees, the temperature inside a car parked in direct sunlight can quickly climb to between 130 to 172.”

– Centers for Disease Control and Prevention

“In terms of heat-rise over time, it makes very little difference whether a car’s windows are closed or partially open. In both cases, a car’s interior temperature can rise approximately 40 degrees within one hour, even when the exterior temperature is only 72°F.”

– American Academy of Pediatrics study (2005)

“Even on a relatively cool day, the temperature inside a parked car can quickly spike to life-threatening levels if the sun is out, researchers at the Stanford University School of Medicine have found. They hope their findings will put to rest the misconception that a parked car can be a safe place for a child or pet in mild weather. ‘There are cases of children dying on days as cool as 70 degrees Fahrenheit,’* said lead author Catherine McLaren, MD, clinical instructor in emergency medicine. Though past research has documented the temperature spike inside a car on extremely hot days, this is the first time anyone has looked at cooler days, she added.”

– Stanford University press release: “Parked cars get dangerously hot, even on cool days, Stanford study finds” (2005)

(*HeatKills.org.: Here in Charlottesville, VA, a toddler died of heatstroke after being left in a car, on a day in which the outside temperature did not exceed 66 degrees.)

“Never leave your pet in a parked car when the outside temperature is above 70 degrees. Not even with the windows partway down, not even in the shade, not even for a quick errand. Dogs and cats can’t sweat like humans, so they pant to lower their body temperature. If they’re inside a car, recycling very hot air, panting gives no relief, and heat stroke can happen quickly.”

– Michael Dix DVM, Medical Director, Best Friends Animal Society

“Heat stroke can permanently damage a pet’s health very rapidly. The change of only a few degrees to a dog’s normal body temperature can quickly result in coma, organ dysfunction, permanent brain damage or even death.”

– Jules Benson, DVM, Medical Director, Pet Plan Pet Insurance

How hot does it get in a car, and how quickly?

This chart helps to answer that question:

Also, Dr. Ernie Ward is a veterinarian you should know. He’s spent many years devoting himself to not only treating illnesses in dogs and cats, but in developing better means for preventing them.

Doesn’t leaving the windows cracked an inch or two make a difference? No.

A study conducted by Red Rover demonstrates that the difference in interior temperature between a car with the windows fully closed, and those that are cracked a few inches, is negligible.