Skip to content

GSOM station files

Available since v0.33 as noaa:gsom-station-files. The Global Summary of the Month is NCEI's set of monthly station summaries derived from GHCN-Daily: means, extremes, totals, and day counts. noaa:gsom reads it through the Access Data Service, which selects months, stations, and elements on the server. This dataset reads NCEI's static per-station files instead: one CSV per station holding its whole record, every element, in metric units.

uv run usdata fetch noaa:gsom-station-files -p stations=USW00094823,USC00100667 --dry-run

When to use which

noaa:gsom noaa:gsom-station-files
Request One query per 50 stations, built by the service One static file per station
Selects Months, stations or a box, and elements Stations only
Units Metric or standard Metric
Speed for long records Varies widely (below) 315 stations, 199 MB, in 49 s

Use noaa:gsom for a few elements over a short window, or to find stations in a box. Use the station files for many stations' long records. On 2026-09-28, a 50-station, 77-year SNOW request to the service streamed at anywhere from 35 kB/s to 4 kB/s, and one stalled past three 120-second read timeouts. The same station's static file, 407 kB, arrived in 0.7 s. The values agree: Pittsburgh's (USW00094823) snowfall for November 1997 to March 1998 is 64, 320, 45, 64, and 125 mm by either route.

Selection

stations is required and takes one GHCN id, a list, or a comma-separated string. Ids are upper-cased, must be 11 characters, and repeat only once. The asset id is <station>.csv, which is NCEI's filename. The files cannot be selected by time, place, or element, so a window, a box, variables, and text are refused, and every capability is false.

NCEI's directory holds one file for every GSOM station worldwide and is too large to list: a request for its index returned nothing in 30 seconds. So listing makes no request and reports no size, and a station without a file fails at fetch with a 404 rather than at listing. For the same reason an asset's time is the archive's bound, from GHCN-Daily's first observation in 1763 and open-ended, not the station's own span, which the file's first and last DATE give.

What a file holds

One row per month, from the station's first summarised month to its last, with STATION, DATE (YYYY-MM), LATITUDE, LONGITUDE, ELEVATION, NAME, and then each element with its _ATTRIBUTES column. The element set depends on the station: USC00100667's file has 68 columns. A month's value is blank when NCEI could not compute it: for precipitation and snowfall, more than five days missing or flagged. Each attribute column is DaysMissing,MeasurementFlag,QualityFlag,SourceFlag, so ,,,Z is a value with no missing days from source Z, and a leading number counts the days missing. Units are metric: millimetres for SNOW and PRCP, degrees Celsius for temperatures, metres for ELEVATION. The asset's properties record units: metric, which the file does not state.

open() returns a pandas DataFrame with STATION kept as a string:

frame = item.open()
winter = frame[frame["DATE"].str[5:].isin(["12", "01", "02"])]

Revisions

NCEI rewrites each file in place as the station's summaries change. The record states weekly updates, and USC00100667's file carried a Last-Modified of 2026-09-16. A lockfile pins each station's file separately, so a revised station reports that one entry as changed and leaves the others alone.

Upstream revisions

Agencies revise files in place. A locked restore downloads each pinned URL and fails with a checksum mismatch when the bytes have changed; accept the new bytes for chosen entries with pull --update, or re-resolve the whole manifest with pull --force. A lockfile detects changed data; it does not archive it. Keep the cache with the manifest and lockfile. See provenance and drift.

Metadata sources

Every value in the catalog entry's resolution, cadence, citation, terms, variables, and limits comes from one of these pages. A field the agency does not publish is left empty rather than estimated.

  • The file location, element definitions, missing-day rules, and attribute layout: NCEI's GSOM documentation, which names https://www.ncei.noaa.gov/data/global-summary-of-the-month/access as where the data files are.
  • Updates, citation, and terms: the NCEI dataset record, the same one noaa:gsom cites.
  • Units: the files, checked against the service's metric output for the same station and months.
  • Latency is empty: the record states no lag between a month's end and its summary.

All NOAA datasets.

Reference

noaa:gsom-station-files · Released · Included since usdata 0.33. Global Summary of the Month Station Files.

At a glance

Parameters

Pass these as --param name=value to the CLI, as params: entries in a manifest, or as keyword arguments to build_query.

Parameter Meaning
stations Required GHCN station id(s): one, a list, or comma-separated.

Variables

Variable Units Meaning
PRCP mm Monthly precipitation total
SNOW mm Monthly snowfall total
SNOW_ATTRIBUTES — Days missing, measurement, quality, and source flags for SNOW
TAVG degrees Celsius Monthly mean temperature

Catalog facts

  • Availability: since 0.33
  • Domain: Surface weather
  • Spatial resolution: Land surface stations, derived from GHCN-Daily
  • Temporal resolution: Monthly
  • Updates: Weekly
  • Terms of use: https://www.ncei.noaa.gov/metadata/geoportal/rest/metadata/item/gov.noaa.ncdc:C00946/html
  • Citation: Lawrimore, Jay H.; Ray, Ron; Applequist, Scott; Korzeniewski, Bryant; Menne, Matthew J. (2016): Global Summary of the Month (GSOM), Version 1. NOAA National Centers for Environmental Information. https://doi.org/10.7289/V5QV3JJ5
  • Geographic bounds (WGS84): west -180°, south -90°, east 180°, north 90°
  • Catalog date range: 1763-01-01 to open-ended
  • Coverage varies by station, product, and date; the range above does not guarantee observations.
  • Upstream documentation
  • License: US Government Work (public domain)
  • Transport: http
  • Adapter: usdata.providers.noaa.gsom_files:GsomStationFiles