Independently reported high or low temperatures

A common source of confusion can arise from observing platforms which submit both regular frequency observations (say, hourly) as well as summary-type statistical measurements, such as a 6 or 24 hour max temperature (variables air_temp_high_6_hour and air_temp_high_24_hour are variables which will exhibit this quality).

It is common for the reported maximum value to be higher than any of the individual reported values. This is because the extreme value indicated is often reported from a more frequent sample of the atmosphere than the regular reports. Though it varies by variable, an hourly report is often a sample of a short period of time around when the report is given. This means that any variations that happened between those reports are not actually shared by the station, but may be considered for the max value reports.

This principle is true even in the case of high frequency reports, at 5 or even 1 minute reporting frequency. Sensors often sample temperatures, for instance, tens or hundreds of times per second.