According to NOAA, ASOS reports the following basic weather elements:
- Sky conditions such as cloud height and cloud amount up to 12,000 feet,
- Surface visibility up to at least 10 statute miles,
- Basic present weather information such as the type and intensity for rain, snow, and freezing rain,
- Obstructions to vision like fog, haze, and/or dust,
- Sea-level pressure and altimeter settings,
- Air and dew point temperatures,
- Wind direction, speed and character (gusts, squalls),
- Precipitation accumulation, and
- Selected significant remarks including variable cloud height, variable visibility, precipitation beginning/ending times, rapid pressure changes, pressure change tendency, wind shift, peak wind.
ASOS continually collects data and submits reports every hour, or any time there is a significant change. The data is transmitted to the NWS as well as directly to planes.
An advantage of ASOS is that it works 24 hours a day, 365 days a year. This means it works at night, when visibility is low and thus human observation is less conclusive. While the primary goal of ASOS is safety for planes, it is a valuable resource for weather forecasting.
A limitation of ASOS is that it only makes measurements of what is directly above it. Therefore, if there is a storm in the distance, ASOS will only report it once the storm moves over the equipment.