ASOS vs. AWOS Weather Stations: What's the Difference?

Published 2026-07-15 · Updated 2026-07-15

Automated Surface Observing Systems (ASOS) and Automated Weather Observing Systems (AWOS) are critical for aviation and weather forecasting, providing vital surface observations, but they differ in their capabilities and primary uses.

ASOS vs. AWOS Weather Stations: Understanding the Data You See

When researching past weather events, you'll often encounter references to data collected by Automated Surface Observing Systems (ASOS) and Automated Weather Observing Systems (AWOS). Both are automated weather stations that report critical atmospheric conditions, primarily for aviation and meteorological purposes. However, they have distinct differences in their sensor suites, reporting capabilities, and the agencies responsible for their deployment and maintenance.

What Are ASOS and AWOS Stations?

ASOS (Automated Surface Observing System): These are the primary surface weather observing systems in the United States, jointly sponsored by the National Weather Service (NWS), Federal Aviation Administration (FAA), and Department of Defense (DoD). ASOS stations provide a comprehensive suite of weather observations, including sky condition (cloud height and amount), visibility, present weather (rain, snow, fog), temperature, dew point, wind direction and speed, and barometric pressure. Many ASOS sites also have additional sensors, such as those for freezing rain or lightning detection. ASOS systems are typically found at larger airports and generate hourly observations, with special observations triggered by significant weather changes.

AWOS (Automated Weather Observing System): Primarily deployed and maintained by the FAA, AWOS units are generally less comprehensive than ASOS, though capabilities vary widely between different AWOS models (AWOS-1, AWOS-2, AWOS-3, etc.). They focus more specifically on aviation needs, reporting parameters like altimeter setting, wind data, temperature, dew point, and density altitude. More advanced AWOS versions (AWOS-3 and above) can also report cloud height, visibility, and present weather. AWOS stations are commonly found at smaller and medium-sized airports.

Key Differences and Similarities

While both systems provide automated weather observations, here's a breakdown of their primary distinctions:

  • Sponsorship & Purpose: ASOS is a collaboration primarily for general weather forecasting and aviation, while AWOS is predominantly an FAA system focused on aviation safety at airfields.
  • Data Comprehensiveness: ASOS generally offers a more extensive set of observations, including detailed sky conditions and present weather, making it a cornerstone for NWS forecasts. AWOS, especially older versions, might have a more limited set of sensors.
  • Reporting Frequency: Both systems typically provide observations every minute, but full coded METAR reports for ASOS are usually issued hourly, with special observations for rapid changes. AWOS reports can be more frequent in some cases.
  • Deployment: ASOS is found at major airports and strategic locations across the country. AWOS systems are more numerous and can be found at a wider range of smaller and regional airports.

Both systems share the common goal of providing accurate, real-time surface weather data using automated sensors, reducing the need for human observers (though human augmentation can still occur, especially at ASOS sites).

How StormAuditor Uses Station Data

StormAuditor leverages surface weather station data, including observations from ASOS and AWOS stations, as part of its comprehensive historical weather analysis. For instance, when analyzing wind events for a specific property-level historical weather report, data from nearby stations can provide valuable context, especially for things like peak wind gust and sustained wind speeds. Our Storm Auditor Wind Estimate (SAWE-2.7) blends this station data with other sources like SPC storm reports and NWS severe thunderstorm warning polygons.

It's important to remember that station data provides point observations. While highly accurate for the immediate vicinity of the station, weather conditions, especially severe weather like microbursts or hail swaths, can vary significantly even a short distance away. StormAuditor accounts for this by integrating data from multiple sources.

For hail events, while ASOS/AWOS typically do not directly report hail size, they can indicate the presence of precipitation, which StormAuditor combines with radar-derived Maximum Estimated Size of Hail (MESH) data via our Storm Auditor Hail Estimate (SAHE-2) for a more complete picture.

Limitations

While ASOS and AWOS stations provide crucial data, it's important to recognize their limitations. They are point observations, meaning a severe event (like a downburst or a significant hailfall) could occur between stations and not be directly measured by either. Station-based wind observations, for example, can under-sample localized wind events like microbursts, meaning the actual peak gust experienced at a property between stations could exceed reported values. Additionally, ASOS and AWOS reports alone cannot provide the precise path of hail or wind swaths that impact properties. This is why StormAuditor integrates radar data and storm reports to provide a more holistic estimate. Learn more about our methodology and limitations here.

Related StormAuditor Tools

FAQ

Q: Can ASOS/AWOS tell me the exact hail size at my property?

A: No. ASOS and AWOS stations do not have sensors to measure hail size directly. They can report the presence of precipitation, potentially identifying hail if a human observer is present or if specific sensors detect it (uncommon for hail size). For hail size estimates, StormAuditor relies on radar-derived MESH data and human-observed storm reports. See our Hail Explorer for more details.

Q: Are ASOS/AWOS wind gusts always accurate for a location miles away?

A: Automated stations provide highly accurate wind measurements at their specific location. However, wind conditions, especially during severe weather events, can vary dramatically over short distances. For example, a microburst might produce damaging winds over a very small area that an ASOS/AWOS station just a few miles away might completely miss. StormAuditor's SAWE-2.7 addresses this by incorporating multiple data sources.

Q: What agency maintains ASOS stations?

A: ASOS stations are a joint venture between the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DoD). This ensures their data is widely available and critical for both aviation safety and general meteorological forecasting.

Q: Do these stations ever make mistakes?

A: While automated systems are highly reliable, sensor malfunctions or environmental factors (like heavy icing on a wind sensor) can occasionally lead to erroneous readings. Meteorologists, as well as StormAuditor's algorithms, apply quality control checks to identify and filter out unreliable data points.