Researching historical weather observations

Treat station identity as part of every measurement

A place name is not a stable observing instrument. Record station name, identifier, network, latitude, longitude, elevation and period. The NOAA Historical Observing Metadata Repository tracks moves, observing times, methods, equipment and siting changes. Retrieve that history before joining values across decades.

Stations can close, merge or change identifiers, and two stations serving one city may have different exposures. Airport, rooftop, harbor and rural observations are not interchangeable. Build a station timeline and flag gaps before calculating comparisons.

Name the data product and temporal scale

Separate manuscript form, daily summary, monthly aggregate, quality-controlled dataset and derived climate normal. NOAA Climate Data Online provides daily, monthly and other products with their own fields and quality processes. Preserve units, observation time, missing-value codes and flags.

A daily maximum, observation-time temperature and monthly mean answer different questions. Precipitation may be assigned to the observation date rather than the moment it fell. Read documentation before combining records or translating a historical notation into a modern variable.

Test changes in exposure and method

Instrument replacement, screen type, station relocation, urban development and observing-time change can create discontinuities. Compare metadata, neighboring stations and original forms around a suspected break. A sharp change can be real weather, a site change or both.

For long-term analysis, use documented homogenized products or explain the adjustment method. One station can support a local event description; regional or climate conclusions need a wider network and uncertainty. Do not infer a trend from selected extremes alone.

Cite values with station and product provenance

Cite agency, dataset or original form, station identifier, element, date range, units, product version, access date and download link. Retain the exact query or file. If a value was corrected or flagged, record the version used and the treatment applied.

Write findings at the scale supported: the station reported, the dataset returns, the regional series indicates. Weather observations become defensible climate evidence only when station history, quality control, comparison and method remain attached.

Working checklist

Use this as a session checklist. Ticks are saved only in this browser; download a worksheet to keep a portable record.

What to record before you leave

• Station identifier, coordinates, elevation and network
• Element, units, observing time and quality flags
• Moves, instruments, product version and download query

Compare with

Station metadata, original forms, neighboring stations and documented regional products.

A supportable conclusion

Station discontinuities and method are disclosed at the same scale as the claimed trend.

Citation structure

Agency and dataset; station and element; dates; product version; query or file; access date.