If your vehicle has an outdoor temperature reading, it's likely wrong.
How many times have you looked down and snapped a photo of the reading during hot weather? Odds are it says something closer to 100° on a day where it's only supposed to be 90°. Does that mean the meteorologist on TV was wrong? No. Not at all.
On warm summer days, the readout on your car can be 10-20 degrees higher than the actual air temperatures. And that's because your vehicle is actually taking a reading of the heat coming back up off the pavement.
Typically, you'll notice a very hot reading on day where we have a lot of sunshine. Here's why.
As the sun bakes into the asphalt through the day, that extreme heat is radiating off the road's surface. Asphalt and concrete can easily be 30-40 degrees hotter than grassy or shaded surfaces.
The outside temperature sensor on your vehicle is usually located in the front of the vehicle, close to the pavement.
So to be fair, it's not that your thermostat is reading the temperature incorrectly, it's just reading the wrong temperature.
And the same thing goes with bank thermometers. The sensor is usually located on the bank's sign, which is typically dark in color (that absorbs heat) and is often in the direct sunlight. How many times have you seen an absurd temperature on one of those signs?
Official temperature readings are taken about six feet off the ground, over a grassy location. These days, most official temperature observation stations are located at airports. This is where TV meteorologists get their temperatures and these are also the values used by the National Weather Service.
So, the next time you jump into your car and it shows you a temperature that seems really hot, odds are it's just measuring the heat coming off the pavement.