Analyze and Export GHCNh Hourly Data

A practical workflow for selecting a NOAA GHCNh station, interpreting hourly and multi-hour observations, checking quality fields, and exporting Excel or source data.

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Open the interactive GHCNh station explorer

GHCNh Explorer map showing the global hourly station network

Quick start

1. Choose a country, then select a station by map marker, search control, or double-clicking its row in Stations Info.
2. Set a UTC date range of no more than 366 days.
3. Use Dashboard → Plots to check timing, gaps and which parameters are actually available.
4. Open Dashboard → Data to inspect the core hourly fields and select Export Hourly Excel.
5. Keep the station ID, UTC interval and download date with your analysis. Use NOAA’s PSV or Parquet files when you need original source codes or bulk access.

What this guide helps you do

The GHCNh Explorer presents NOAA/NCEI Global Historical Climatology Network hourly and synoptic observations from fixed land stations. The Explorer is useful for finding stations and inspecting a bounded interval; NOAA remains the authoritative source for definitions, revisions and source-level flags.

This page owns the practical workflow: selection, interpretation, quality checks and export. For broad browsing, use the interactive GHCNh Explorer. For an evidence-led example of what hourly data can reveal, read the Dubuque nighttime-heat analysis.

Select a station and time window

• Select Country narrows the station network without implying that every station has the same variables or record length.
• Find Station searches the filtered catalog. Confirm the station name and 11-character GHCN identifier before analysis.
• Map View selects a station spatially; Stations Info is better when similar names or nearby stations need to be distinguished.
• Select Date Range uses UTC and is limited to 366 days. Move the window to inspect another year rather than combining unrelated periods.
• Download Stations (Excel) exports the station inventory currently visible under the country and map filters; it does not export observations.
• Full Screen View: Click the Maximize / Full Screen button in the top-right corner of the explorer window to expand the dashboard to full display size. This is recommended when inspecting complex multi-panel charts, high-density station maps, or large data tables. Press Esc or click the icon again to exit.

Preserve station identity

A place name is not a unique station key. Record the GHCN identifier, coordinates, elevation and period of record shown in the dashboard header. Airport, urban and elevated sites can describe different local conditions even when their names contain the same city.

Read the current dashboard correctly

After a station loads, Plots shows only panels supported by the selected records. Depending on availability, these may include temperature and dew point, relative humidity, wind and gusts, sea-level or station pressure, visibility, precipitation accumulations and a wind rose. Missing panels usually mean that the parameter is absent for that station and period—not that the weather phenomenon did not occur.

The summary cards describe the selected window. They are not climatological normals, official records or a guarantee of 24 observations per day. Check the timestamps and gaps before calculating extremes or durations.

Data displays the core parsed hourly fields and provides the current Export Hourly Excel control. The application does not currently provide a separate daily-data table or daily export.

GHCNh dashboard showing hourly station plots for the selected interval

GHCNh Data tab showing the hourly table and Excel export

Core displayed and exported fields

The table on screen focuses on a small set of parsed variables. The downloaded workbook contains the parsed records for the selected interval and may include additional raw, measurement, quality and source fields used by the application.

Core fields displayed in the GHCNh hourly table

Explorer field	Meaning	Unit or time basis
datetime	Observation timestamp	UTC
temp	Near-surface dry-bulb air temperature	°C
dew_point	Dew-point temperature	°C
rh	Reported or source-derived relative humidity	%
pressure	Sea-level pressure	hPa
wind_speed, wind_gust	Sustained wind and peak short-duration gust	m/s
wind_dir	Direction from true north; calm reports may use 0	degrees
precip	Nominal hourly liquid-equivalent precipitation; intermediate reports can occur	mm
vis	Horizontal visibility	km

Source and interpretation fields that may accompany exported records

Field group	Safe interpretation
precip_3h … precip_24h	Separate liquid-equivalent accumulation totals ending at their report time; do not add overlapping intervals together
*_code in the Explorer export; *_Measurement_Code in NOAA PSV	Describes how a value was reported, such as trace or accumulated-period status; meanings can depend on source
*_qc in the Explorer export; *_Quality_Code in NOAA PSV	Records integrated or legacy QC information; code meanings are source-dependent
*_source and *_report_type aliases	Identify the contributing stream and report type needed to interpret measurement and QC codes
raw and parsed value pairs	Preserve the source value alongside the application-ready numeric value; use the raw NOAA row for audit-sensitive work

Reconcile multi-hour precipitation

GHCNh can carry precipitation totals over 3, 6, 9, 12, 15, 18, 21 and 24 hours. These columns are alternative accumulation periods, not independent hourly buckets.

Use this workflow:

1. Choose one accumulation duration that matches the question—for example, precip_6h for reported six-hour totals.
2. Treat the timestamp as the end of that reported accumulation unless the source documentation indicates otherwise.
3. Do not sum a 3-hour and a 6-hour value reported at the same time; their periods may overlap.
4. Inspect the associated measurement, quality, report-type and source fields in the NOAA PSV when completeness or trace handling matters.
5. Do not construct a daily total by mixing durations. Prefer an official daily product such as SSOD when the task is a daily meteorological summary.

NOAA documents precipitation as nominally hourly, but it can include intermediate reports. Multi-hour fields from FM12/SYNOP reports are explicitly accumulation totals. A blank accumulation is missing or unavailable information, not zero precipitation.

Calculate dew-point depression

Dew-point depression is the air temperature minus the dew point at the same timestamp:

\[D = T - T_d\]

Both inputs must use the same temperature unit. In the Excel export, create a new column with a formula equivalent to temp - dew_point. A smaller non-negative difference generally indicates air closer to saturation; it does not by itself prove fog, cloud, precipitation or a heat hazard.

Before using the calculation:

• keep only rows where both temp and dew_point are present;
• do not pair values from different timestamps;
• retain the original fields and QC/source columns;
• investigate any negative result rather than automatically converting it to zero.

Apply quality checks without misreading flags

GHCNh combines many contributing sources. NOAA applies general checks to a subset of variables and preserves quality information inherited from component sources. Therefore, the same code can have different meaning under different source codes.

The Explorer masks documented bad codes for several core parsed variables, including temperature, dew point, wind, nominal hourly precipitation, pressure, humidity and visibility. This produces cleaner plots, but it is not a guarantee that every retained value is correct or that every parameter received the same QC treatment.

For reproducible filtering:

1. retain measurement, quality, source and report-type fields;
2. interpret codes using the matching source section in NOAA’s GHCNh documentation;
3. distinguish not checked, missing QC code, suspect, erroneous, calculated and derived;
4. remember that NOAA’s 9-Missing QC label means no QC code was supplied—it does not automatically mean the observation value is missing;
5. document every exclusion rule and compare results before and after filtering.

Export options

Choose the access route according to the task:

• Download Stations (Excel) exports the filtered station catalog.
• Export Hourly Excel exports parsed observations for the selected station and date window.
• NOAA period-of-record station files provide source PSV files named GHCNh_<station-id>_por.psv.
• NOAA GHCNh bulk access provides PSV and Parquet routes better suited to larger workflows.

For example, the direct period-of-record file for Tokyo (JAI0000RJTD) is GHCNh_JAI0000RJTD_por.psv.

Reproduce the Dubuque example

Open the Dubuque Regional Airport hourly view. Confirm station USW00094908, keep the interval at 29 June–1 July 2026, inspect temperature and dew point in Plots, then export the hourly workbook from Data.

The related article uses one valid temperature-and-dew-point report per local clock hour for threshold counts. That editorial analysis is not the Explorer’s default aggregation and is documented separately in the Dubuque nighttime-heat evidence story.

Troubleshooting

• The requested interval will not load: Reduce it to 366 days or less.
• The station has no plot for a parameter: Try another interval and verify the station inventory; coverage varies by source, sensor and era.
• The station list changed after moving the map: The station download follows the active country and visible-map filters.
• The export is not CSV: The current interface exports .xlsx; use NOAA’s PSV or Parquet access for text or columnar source formats.
• An accumulation looks too large: Check its duration and ending timestamp before comparing it with an hourly value.
• You need an official daily value or record: Use the responsible national service or NOAA daily product and its day definition; do not infer an official daily record from a selected hourly window.

Authoritative references

• NOAA/NCEI GHCNh product page
• NOAA GHCNh documentation
• NOAA GHCNh metadata and citation