A term of the record

ASOS

Automated Surface Observing System. The network of automated weather stations, mostly at airports, that records the official surface observations of wind, temperature and precipitation.

Definition

Related pages: 4
Last revised: 23 August 2026

ASOS is the network of automated surface stations run by the National Weather Service, the Federal Aviation Administration and the Department of Defense, sited mostly at airports because aviation is what they were built for. Each station measures wind, temperature, dew point, pressure, visibility, precipitation and sky cover continuously and reports on a fixed schedule, with a special report whenever conditions change past a threshold. Its wind sensor stands at a standard height over open ground, and its readings are the official observations of record for the place.

A station observation is the most defensible kind of wind figure there is: an instrument, calibrated to a federal standard, reporting on a fixed schedule, with the sustained wind and the peak gust both kept. It is also an observation at the station, and nowhere else. Stations are tens of miles apart, sited on flat open ground, and a thunderstorm's strongest wind falls in a swath narrow enough to miss every station in the county. A reading that a storm produced no severe gust at the airport says nothing about the subdivision the storm actually crossed, and a reading that it did says that much and no more.

The product files a station reading as a weather station observation, measured, and always prints the distance from the address to the station beside it, because that distance is the whole of what separates the reading from the roof. It does not measure hail; a station records precipitation as depth of water and does not report stone size.

In the report

How the document prints it

In the report a station reading appears as a weather station observation with its time, its sustained wind and peak gust where both were reported, and the distance from the address to the station, marked as measured; its citation under Sources and method names the nearest official station as the scope searched. The hourly values in the wind section are not station readings: they are a gridded analysis over the address itself, qualified as analyzed, and the document keeps the two apart by the column they sit in and the word beside them.

The terms this page uses and the guides that go further. Each is shown against its own example from the record.

Term Peak gust
The highest wind speed recorded over a brief interval, a few seconds, at a station or by an observer during a storm or a day.
Term Sustained wind
The wind speed averaged over a fixed interval of a couple of minutes at a station, as distinct from the peak gust within it.
Term Cooperative observer
A volunteer who takes daily weather measurements at a fixed site with issued instruments and files them with the National Weather Service.
Guide Automated weather reports in court: what survives a challenge
Two Florida courts excluded wind figures taken from commercial weather products because nobody could verify how they were made. This guide states what those rulings turned on, what Rule 702 asks of a figure and of the person citing it, what independent corroboration means as a count, and what a report has to say about itself to be cited.

Sources

The primary references. Each opens on the agency's own site.

The next step

The glossary defines the word. The report is what uses it.

Everything above is definition: what the word means in the document, and what it does not. None of it says what reached one roof.

Run the address and the archive is searched at the property: the storm, the date, the measured size, the distance and bearing from the roof, and the federal record each figure came from, in a document that states its own method. About a minute.

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How this page is made

The text: Written by the editors and last revised 23 August 2026. It explains the record and how the report reads it; it contains no figure of its own.
The example: The archive holds nothing this page could show yet, so no example is printed. One appears, computed rather than written, as soon as the record holds a relevant day.
Measured and detected: A report from a person or an instrument is measured. A radar-derived size is detected, not measured, and is marked as such, here and in every document we issue. The two are never added together.
What this is not: A definition of a word the report uses. It is not a report on any property, and it states no opinion about one. The coverage page states what the record holds, by kind and by year.

About this record

Everything here is reproduced from public federal and volunteer weather records, as the agencies and observer networks that publish them released it. Titan Weather compiles the record; it does not observe the weather, and it is not affiliated with any source it cites.

No archive holds everything. Storms cross places where nobody is standing, instruments and spotters cover some areas better than others, sources revise their records, and recent reports can take weeks to arrive and settle. Where this page shows nothing, nothing was found in the sources searched, within the period and area it states. That is not a finding that no weather occurred.

These pages describe the public record near a place or on a date. They do not establish what reached any particular property, and nothing here is insurance, legal or engineering advice.