Why 'Bank Thermometers' Can't Be Trusted

Bruce Yuangyue Bi/Lonely Planet Images/Getty Images

Updated July 11, 2015

Have you ever been sitting in traffic on a hot and humid summer day or a blustery winter's day and wondered exactly just how hot or cold it is? If you happen to pass a bank or credit union, you may see the temperature displayed on an outdoor LED display, but in truth, this temperature is likely wrong. 

Bank thermometers almost always display inaccurate readings, either because the temperature data isn't measured on-site, or if it is, there are errors in how the built-in temperature sensor takes its measurements.

Not All Signs are Equipped with Temperature Sensors  

A few of these types of electronic signs are fed their advertising content, including weather, from a subscription service. The problem with this is that the temperature data displayed may be from the city's airport weather observing station miles away rather than the specific temperature at that exact location.  

Poor Thermometer Positioning Leads to Erroneously High Temperature Readings

Getting an accurate temperature reading from any thermometer starts with where the thermometer is placed. As any good meteorologist or weather observer will tell you, the golden rule of measuring air temperature is to place the thermometer in a shaded location. (This ensures that the actual ambient air temperature--not the temperature of the thermometer warmed by the sun--is recorded.) Not only are most bank thermometers exposed to direct sunlight, but what's worse, they're located above the dark asphalt of a parking lot.

If you've ever touched or walked barefoot on a paved surface, you know firsthand that it absorbs more incoming solar radiation than the surrounding ground; as the pavement absorbs these high levels of heat, it in turn heats the air above it, which can cause the temperature sensors to record much higher values than what the air temperature is in reality--up to tens of degrees higher!

 

So the next time you happen to pass by one of these LED display signs, remember to take its temperature reading with a grain of salt. You'd do better to listen for the weather announcement on your favorite local radio station.