Definition
An AIRMET (AIRmen's METeorological Information), identified by the product code WA, is an in-flight weather advisory issued by the National Weather Service to alert pilots of weather phenomena that may be hazardous to aircraft, particularly those of single-engine, light, or otherwise weather-sensitive types, but at intensities below the level requiring a SIGMET. AIRMETs cover moderate icing, moderate turbulence, sustained surface winds of 30 knots or more, widespread areas of ceilings less than 1,000 feet and/or visibility less than 3 miles, and extensive mountain obscuration.
Plain English
A WA, or AIRMET, is a weather warning aimed mainly at pilots of smaller aircraft. It tells you about widespread weather that's bad enough to matter — like moderate icing, moderate turbulence, strong surface winds, or large areas of low clouds and poor visibility — but not severe enough to trigger the more serious SIGMET warning.
Context Anchor
Pilots see WA — AIRMETs during preflight weather briefings, in aviation weather apps, and on weather products used for route and go/no-go decisions.
Derivation
WA is simply the product code the weather service stamps on AIRMET bulletins. AIRMET is built from 'airmen' + 'meteorological,' meaning weather information for airmen. Knowing the code helps you recognize the bulletin instantly when scanning a stack of weather products.
Why Pilots Care
The advisory helps a pilot decide whether the reported conditions exceed the capability of their aircraft or their own experience before takeoff or en route.
Grounding Statement
If the weather along your route is not extreme enough for the highest-level warning but is still likely to matter for safety, it may appear as a WA — AIRMET.
Intuition Check
WA here does not mean Washington. In this context, WA is the FAA weather product identifier for an AIRMET.
Example Sentence 1
During his preflight briefing, the pilot noted an active WA for moderate icing between 8,000 and 14,000 feet along his route and decided to file at a lower altitude.
Example Sentence 2
Because of the AIRMET for IFR conditions, the pilot filed an instrument flight plan instead of departing VFR.