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

By StormAuditor Editorial Team · Published 2026-07-15 · Updated 2026-08-11

Based on public NOAA and National Weather Service records, published under StormAuditor's methodology and data-source standards. Radar-derived hail sizes are estimates unless attributed to a ground report.

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 you research past weather events, you will often see data from Automated Surface Observing Systems (ASOS) and Automated Weather Observing Systems (AWOS). Both are automated weather stations. Both report key atmospheric conditions, mainly for aviation and weather forecasting. But they differ in their sensors, their reporting, and the agencies that run and maintain them.

What Are ASOS and AWOS Stations?

ASOS (Automated Surface Observing System): These are the main surface weather observing systems in the United States. They are jointly sponsored by the National Weather Service (NWS), Federal Aviation Administration (FAA), and Department of Defense (DoD). ASOS stations report a full suite of weather observations:

  • Sky condition (cloud height and amount)
  • Visibility
  • Present weather (rain, snow, fog)
  • Temperature and dew point
  • Wind direction and speed
  • Barometric pressure

Many ASOS sites carry extra sensors, such as ones for freezing rain or lightning detection. ASOS systems sit at larger airports. They issue hourly observations, plus special observations when the weather changes fast.

AWOS (Automated Weather Observing System): The FAA deploys and maintains most AWOS units. They are usually less complete than ASOS, though capabilities vary widely between AWOS models (AWOS-1, AWOS-2, AWOS-3, etc.). They focus on aviation needs. They report items like altimeter setting, wind data, temperature, dew point, and density altitude. More advanced versions (AWOS-3 and above) can also report cloud height, visibility, and present weather. AWOS stations are common at smaller and medium-sized airports.

Key Differences and Similarities

Both systems give automated weather observations. Here are their main distinctions:

  • Sponsorship & Purpose: ASOS is a joint effort for general weather forecasting and aviation. AWOS is mainly an FAA system focused on aviation safety at airfields.
  • Data Comprehensiveness: ASOS usually offers a wider set of observations, including detailed sky conditions and present weather. That makes it a cornerstone for NWS forecasts. AWOS, especially older versions, may have fewer sensors.
  • Reporting Frequency: Both systems typically take observations every minute. Full coded METAR reports for ASOS usually come out hourly, with special observations for rapid changes. AWOS reports can be more frequent in some cases.
  • Deployment: ASOS sits at major airports and strategic locations across the country. AWOS systems are more numerous. They appear at a wider range of smaller and regional airports.

Both systems share one goal: accurate, real-time surface weather data from automated sensors. This reduces the need for human observers, though humans can still add to the data, especially at ASOS sites.

How StormAuditor Uses Station Data

StormAuditor uses surface weather station data, including ASOS and AWOS observations, as part of its historical weather analysis. For example, when we analyze wind events for a property-level historical weather report, nearby station data adds useful context. This helps most with peak wind gust and sustained wind speeds. Our Storm Auditor Wind Estimate (SAWE-2) blends this station data with other sources, like SPC storm reports and NWS severe thunderstorm warning polygons.

Remember: station data gives point observations. A station is very accurate for its own spot. But weather, especially severe weather like microbursts or hail swaths, can vary a lot even a short distance away. StormAuditor accounts for this by combining data from multiple sources.

For hail, ASOS/AWOS typically do not report hail size directly. They can show that precipitation occurred. StormAuditor combines that with radar-derived Maximum Estimated Size of Hail (MESH) data through our Storm Auditor Hail Estimate (SAHE-2) for a fuller picture.

Limitations

ASOS and AWOS stations provide crucial data, but they have limits. They are point observations. A severe event, like a downburst or heavy hailfall, could happen between stations and go unmeasured by both. Station-based wind observations can under-sample localized wind events like microbursts. That means the actual peak gust at a property between stations could exceed reported values. Also, ASOS and AWOS reports alone cannot map the exact path of hail or wind swaths that hit properties. That is why StormAuditor adds radar data and storm reports to build a more complete 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 have no sensors that measure hail size directly. They can report that precipitation is present. They may flag hail if a human observer is on site or if certain sensors detect it, which is 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 measure wind very accurately at their specific location. But wind, especially in severe weather, can change a lot over short distances. A microburst might hit a very small area with damaging winds. An ASOS/AWOS station just a few miles away could miss it entirely. StormAuditor's SAWE-2 addresses this by using multiple data sources.

Q: What agency maintains ASOS stations?

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

Q: Do these stations ever make mistakes?

A: Automated systems are very reliable, but errors happen. Sensor malfunctions or conditions like heavy icing on a wind sensor can cause bad readings. Meteorologists, and StormAuditor's algorithms, apply quality control checks to find and filter out unreliable data points.