Definition
A ground-based system of weather sensors at or near an airport that automatically measures local weather conditions — typically wind, visibility, cloud height, temperature, dew point, and altimeter setting — and broadcasts the current observation continuously by radio and, at many sites, by telephone. AWOS reports are updated about once per minute and are used by pilots for preflight planning and for current conditions during arrival and departure.
Plain English
A set of weather instruments at an airport that takes its own readings and reads them out over a radio frequency, so pilots can hear the latest local weather without needing a human observer.
Context Anchor
Pilots commonly use AWOS before takeoff, before landing, and while planning an instrument flight to learn the current weather at an airport.
Derivation
The name describes the system literally: 'automated' (runs without a human), 'weather observing' (measures the weather), 'station' (a fixed installation). The point worth noting is that earlier airport weather reports relied on a trained human observer; AWOS replaced that role with sensors and a synthesised voice.
Why Pilots Care
Gives pilots the real-time weather they need to decide whether conditions are safe for takeoff or landing and whether to divert to an alternate airport.
Intuition Check
Do not treat AWOS as a forecast or as air traffic control. It reports current measured weather at that location; it does not predict future weather or issue instructions.
Example Sentence 1
Twenty miles out, she tuned the AWOS on 118.025 and copied the wind, altimeter, and ceiling before calling the CTAF.
Example Sentence 2
AWOS reported a 300-foot ceiling, so the pilot elected to fly the instrument approach instead of continuing VFR.