Remember that "official" temperature reports are taken from calibrated thermometers located in shaded, vented, boxes 10 feet off the ground and specifically located well away from ambient heat sources (asphalt, buildings, etc.) That is often VERY different than actual temperatures at ground level in a specific location such as over asphalt. Also, the thermometers in cars are not calibrated against NIST reference standards. Lastly, temperature, being a very localized measurement of the average heat in the parcel of air immediately surrounding the sensor tip, can vary widely over as little as a few dozen feet laterally or vertically, even if there is no air movement.
For instance:
1) At my airport, the automated weather station, the control tower based sensors, and the NIST-calibrated thermometer in my airplane often differ by 5-15 degrees F
2) My home is located on a ridge 1000 feet above the elevation of my airport. Air temperature normally lapses at 2 degrees C per 1000 feet vertically, so it is always "cooler" in my driveway than it is 1 mile laterally and 1000 feet lower at the airport, all other conditions being equal.
So, assume the external temperature readout in your car is advisory, not tactical, information.