This makes me sad and angry, because it is so bloody preventable, yet it keeps happening. Now, this year, an all-time high number of children have died suffering until they pass in a hot car. It is inexcusable and so avoidable.

Twenty-nine children have died of heatstroke after being left in a vehicle as of the end of July, the most since they've been recording the data at noheatstroke.org.

Even on an 80-degree day -- which is a mild summer day for most of the country -- you're go to 109 degrees in 20 minutes inside a car.

Even when outside temperatures are as low as 57 degrees Fahrenheit, the temperature within a car can climb to 110 degrees, according to the National Highway Traffic Safety Administration.

So how does heat kill kids?

The central nervous system is not fully developed in children, and this makes their bodies less able to cope with temperature changes, according to the Mayo Clinic. Children have difficulty remaining hydrated for this same reason. And as a child's core body temperature rises, heatstroke may occur. That can cause alterations in consciousness and lead to permanent brain, heart and kidney damage. In a worst-case-scenario, heatstroke places a person -- child or adult -- at risk of death.