Plain English Meaning

/RM marks the start of the extra notes at the end of a weather report. Anything written after it is added detail that the main part of the report did not cover.

Full Definition

In a METAR or TAF, /RM is a separator code that introduces the Remarks section. Everything after /RM contains supplementary information not included in the main body of the report, such as observed weather phenomena, sea-level pressure, hourly precipitation amounts, and station-specific notes.

Context Anchor

Seen in the coded format of PIREPs in aviation weather reports.

Derivation

RM is short for 'Remarks,' from the Latin re- (again) and marcare (to note or mark). A remark is something noted in addition. The separates this added section from the report body.