Definition
In a METAR weather report, RA is the contraction used to indicate rain — liquid water droplets falling from clouds, large enough that they do not evaporate before reaching the ground. RA appears in the present weather group of the report and may be combined with intensity prefixes (− for light, no symbol for moderate, + for heavy) and with descriptors such as SH (showers) or TS (thunderstorm), for example -RA, +RA, SHRA, or TSRA.
Plain English
RA is how a METAR says it is raining. A minus sign before it means light rain, nothing in front means moderate, and a plus sign means heavy.
Context Anchor
Seen in the weather section of a METAR, where current conditions at an airport are reported in short codes.
Derivation
RA is a shortened form of the English word rain, kept to two letters so weather reports stay compact and standardized worldwide.
Why Pilots Care
Rain reduces visibility, changes runway friction, and affects takeoff, landing, and aircraft performance decisions.
Intuition Check
Do not read RA as a general forecast or as rain somewhere nearby. In a METAR, RA reports rain occurring at the station at the time of the observation.
Example Sentence 1
The METAR showed -RA BR, so the pilot expected light rain with mist and reduced visibility on arrival.
Example Sentence 2
With RA reported in the current weather, the crew reviewed braking action and visibility before landing.