GHCNm

Explore the NOAA Global Historical Climatology Network monthly (GHCNm) dataset with an interactive Climate Explorer dashboard.

NOAA GHCNm overview

The Global Historical Climatology Network Monthly (GHCNm) archive consolidates quality-controlled observations from tens of thousands of land stations dating back to the 18th century. The current v4 release blends monthly mean temperature and precipitation statistics, adds automated homogenization to reduce non-climatic shifts, and continues to receive new updates from active stations via the NOAA National Centers for Environmental Information (NCEI).

Why this dataset matters

• Provides a globally consistent baseline for comparing climate signals between continents, regions, or single stations.
• Offers homogenized series that correct for instrument changes, relocations, and reporting gaps, which is crucial for long-term trend detection.

Coverage and refresh cadence

GHCNm v4 currently spans 1750 through 2025 (station dependent). New station files are ingested monthly, with NOAA applying additional quality flags before publication. Climate Explorer ingests the public release within a few days to keep the explorer synchronized with the upstream reference archive.

Use the interactive explorer

Interact with the web app to discover individual stations, compare anomalies, or export CSV summaries. Use the panel controls to filter by variable, anomaly baseline, and map region. If the embed below does not load inside your browser, follow the fallback link to open it in a separate tab.

Having trouble viewing the map? Launch the experience directly on Hugging Face Spaces.

Data source and code

• Dataset: We have used the GHCNm Version 4 dataset available at https://www.ncei.noaa.gov/data/global-historical-climatology-network-monthly/v4/temperature/archive/.
• Data source flags: Definitions are documented at https://www.ncei.noaa.gov/data/ghcnm/v4/temperature/doc/ghcnm-flags.
• Source code: Repository: https://github.com/alexdum/ghcnm. Report issues or feature requests in the repository tracker.

Source material and citation

• Official NOAA documentation for the dataset is available through the NCEI GHCNm landing page.
• When referencing results, cite NOAA/NCEI as the data originator and include the Climate Explorer URL so readers can reproduce the visualization workflow.
• For methodology details, consult the v4 technical note and quality-control addenda included on the official download page.