That's so sad. Here's a link to a similar story. It has a chart that shows how quickly the temperature rises in a car even with windows open and even when the temperature is only 75 outside. This happens way too often. If you google it, there are so many cases of two and three year old children being left in the car and dying. So terribly sad.
Golden Retriever Service Dog Left in Car for 2 Hours – Dies | The Daily Golden