For amateur meteorologists it is not always easy to calibrate their equipment, unless you yourself are working at a meteorological service or know people who do, it can be difficult to get the readouts correct within the limits of error of the weather station. I described this already a short time ago.
The Davis Vantage PRO 2+, the hardware which forms the basis of the PWS De Wilgen is not a measurement device without flaws. As any measuring device – a thermometer, hygrometer etc… – it requires calibration and a calibration needs to be checked regularly. I use two types of calibration.