Special Meteorological Reports (SPECI)

Special observations will be taken promptly to report changes that occur between scheduled transmission times whenever changes to the ceiling, visibility, sky condition, precipitation, wind or temperature occur. The amount of change is measured with reference to the preceding routine or special observation.

The criteria for the issuance of a SPECI is not important, however, what a pilot must know is that a SPECI is issued when changes in weather may affect aviation safety and/or operations. These changes do not necessarily represent worsening weather, SPECIs are also issued if the weather improves.