Dr. Ernie Ward spends a half hour in a car on a 94-degree day with the windows cracked. In five minutes, the car is nearing a 100 degrees.
He's showing what can happen in just 30 minutes when you leave your dog in a hot car. It's willful ignorance to think that you can lower your windows about an inch and expect your dog to be alive when you return.
A law went to effect a year ago that protects Good Samaritans who break into a car to save a dog's life. So keep a tire iron or baseball bat in your car and spend a little extra time driving around the parking lots. A window slightly lowered is an indication that a dog may be inside. Stop and get a better look.
Please, don't just limit your search for animals. It's probably something none of us would ever expect to see in our lifetime, but you must check to see if there's any sign that a child might have ridden in the car. If you see toys or a car seat, stop and look inside. Check the floorboard.
You can't case the car for a break in, but that quick look may save a child's life.
I'll leave you with some quotes from heatkills.org about the danger of leaving children or animals in cars. It says children have died in cars when temperatures are at 63 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
“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 (source data here)
“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)