Why your car’s temperature can be misleading

We all know the feeling of getting into a hot car and glancing over at the temperature on the dash and thinking “that can’t be right”. Often times, the temperature recorded and displayed by cars can be several degrees hotter or cooler than reality. This is a result of how vehicles measure temperature.

Cars use a special device called a thermistor to measure temperature, but in a unique way. A material’s electrical conductivity (how well/resistance-free electricity can flow through a given material) can change based on the ambient temperature. A thermistor measures changes in the electrical conductivity for a material (in this case air).

The reason why the temperature shown by your car can be so off comes down to its placement in the vehicle. Normally, a thermistor is housed just behind the grill. Thus, it sits fairly close to the ground.

Dark surfaces (like asphalt) absorb more energy from the sun and subsequently emit that radiation/heat energy back into the atmosphere. The excess heat energy changes the conductivity of the air and is registered by the thermistor, reporting a higher value than the actual air temperature. Another good example is when you turn on your car in the shade and it records a lower temperature than reality.

The surrounding environment influences the thermistor and explains why temperatures from your car can differ from a weather app or your First Alert Weather Team's forecast.

Have you downloaded the 'KESQ First Alert' app yet? It's FREE! Click here