This summer has proven to be one of the hottest on record, and we’re only now in mid-July! Even when the weather is mild, temperatures in cars can soar to dangerous levels within minutes.

We decided to do an experiment with the Kestrel 4500 Bluetooth unit to see just how hot the inside of a car could get during one of the hottest day of the summer. Check out the latest episode of KestrelTV where Kestrel Weather girl Monica Devlin shows you how your car becomes an oven under the hot sun.

It should be noted that we did place the Kestrel in direct sunlight. In meteorology, temperature sensors are always placed in the shade with good airflow. We did this because we were measuring the temperature on the dashboard. Temperature measurements in other parts of the vehicle were likely less than measured on the dashboard, but still significant. The dashboard surface is said to be similar to the hard parts of a child’s car seat in terms of how it much it can heat up.

Graph of Temp (F) and Relative Humidity (%) of our Kestrel in a Car experiment. The data before the temperature begins to rise is from using the Kestrel on a tripod and vane mount to monitor conditions during the early afternoon.

Notice how there is hardly any humidity in the vehicle. Since the low humidity would encourage efficient sweating, any person or animal placed in the car would be dehydrated very fast. Also notice not just how hot it gets but how fast the temperate rises just within the first ten minutes.

Jan Null, Adjunct Professor of Meteorology at SFSU has done extensive research on this topic and provides an up-to-date page on the current statistics and research. His experiments covered a large range of temperatures and he says that “‘cracking the windows had little effect.”

You can download the data from our experiment below. The file is split into four sheets: an introduction, the raw data, the raw data with explanations and finally, a graph. You can investigate the data yourself and make graphs of different things. (Note, we took out data like wind speed that didn’t make any sense to include.) Download the data here (.xls file)

You can find more details for Jan Null’s website here: http://ggweather.com/heat/

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