Why you shouldn't completely trust the temperature in your car

Weather Wednesday temperatures
Car thermometers can't be completely trusted due to the location of the thermistors. (WDAY)

FARGO — We have had two days in the 90s so far in 2020, but you may have noticed on those days that your car and some bank thermometers read triple digits.

Thermistors, a resistance thermometer, measure the change in electrical current as heat is added or removed.

A traditional thermometer has liquid inside which will expand with heat to make the temperature climb higher.

The main problem with the thermistor is where it's located.

It's either under the hood of your car or behind the grille. And the problem with that is, you're so close to the ground that heat will actually radiate from the ground to be very close to where the thermistor is located.


That could add as much as 10 degrees to the temperature you see inside your car.

That's what makes the dashboard temperature seem hotter than the official temperature. The same thing can happen with bank and building thermometers.

They are often placed on a roof or mounted high on the metal siding, both reflect extra heat and can increase the temperature reading. The actual temperatures storm tracker meteorologists use are recorded inside a Stevenson box.

A thermometer is placed in the shade of the white box at roughly four feet above the ground. That's the height that most of us feel temperature at our core, instead of down low by the hot highways or up on a hot tin roof.

And triple digits are a bit of a rarity around here; we see 100 degrees only about once per decade.

The last official one-hundred degree day in Fargo was in 2012. Grand Forks hasn’t officially hit a hundred since 1995.

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