How is temperature displayed in a METAR/SPECI if it is unavailable?

In METAR and SPECI reports, temperature is a critical piece of information that is typically included to provide an accurate depiction of current weather conditions. When temperature data is unavailable, the protocol dictates that the entire temperature group will not be coded in the report. This means that instead of using a placeholder or default value, such as zero or a standard temperature, the absence of temperature information is indicated by simply omitting that specific data group altogether from the report.

This approach maintains the integrity of weather reporting, ensuring that meteorologists and forecasters are aware that the temperature measurement could not be obtained or is not applicable for that observation. It allows users of the report to distinguish between values that were not entered and those that may be considered erroneous or default.