Four facts travel with every value: where the sensor sits, when it was last checked against a reference, what unit it reports, and what the machinery was doing at that moment. Strip one away and the number becomes an opinion.
Fan state matters more than most operators expect. Compost temperature with the fan running, and the same probe ten minutes after it stopped, are not the same measurement. Write the process state beside the value every time, so the batch record can be read a month later by somebody who was not standing there.