What CLIMAT Messages Contain—and How to Explore Them
A CLIMAT report can tell you a station’s average temperature for a month, how much precipitation accumulated and which extremes were reported. It does not preserve the complete sequence of daily weather. That distinction matters when a smooth monthly chart is used to describe a short heatwave or rainstorm.
The World Meteorological Organization (WMO) defines CLIMAT reporting for international exchange of monthly land-station summaries. DWD’s Climate Data Center makes these reports accessible through raw-message tables and separate parameter files. Those products have different formats and quality-control stages.
A monthly summary contains several kinds of information
The WMO CLIMAT template includes measurements, station information and completeness fields. Its temperature fields distinguish the monthly mean from the month’s maximum and minimum. Precipitation fields describe accumulation and defined threshold-day counts. Other fields cover pressure, moisture and sunshine, depending on what the station reports.
The completeness fields matter as much as the headline value. A reported mean with missing daily observations needs to be read with that information attached. An unreported variable is not zero, and two stations need not supply the same set of fields.
A useful way to read a report is to separate three questions: where and when, which statistic, and how complete. Keep those answers together when moving values into a spreadsheet or chart.
The current encoding template is not every archive’s file format
WMO’s conversion template uses BUFR, a binary format for exchanging meteorological observations, with sequences 3-01-150 and 3-07-073. DWD’s public raw archive has its own documented text layout, and its parameter products use another layout. A column name or unit from the conversion template should not be assumed to describe a DWD text-file column.
For example, DWD’s monthly mean-temperature parameter documentation describes rows containing a year and twelve monthly values in Celsius. The WMO conversion template expresses its air-temperature field in kelvin. Both can represent temperature, but reading one with the other’s unit would produce the wrong interpretation. Use the documentation for the file you actually downloaded.
Recent records have not completed the historical checks
DWD separates raw CLIMAT tables from parameter products. Within the parameter archive, recent and historical are separate stages.
For monthly mean temperature, DWD explicitly says the recent product has not passed full quality control. Its historical product has completed the documented checks. The directory name qc therefore does not establish that every recent value is final.
Keep the parameter, source branch, file and retrieval date when using a series. Quality control can identify suspect data, but it does not by itself remove the effects of every station move, instrument change or observing practice. A long-term comparison still needs station history and an appropriate method.
A monthly date is a label, not a one-day observation
The WMO Climate Explorer parses the DWD parameter files for station maps, tables and plots. In this application, a date such as 2026-07-01 labels the July 2026 monthly record. It does not mean that the reported monthly total fell on 1 July.
The Dashboard’s summary cards describe the loaded series, which can mix calendar months. They are not automatically 30-year climatological normals. For a meaningful January comparison, isolate January values and choose an explicit reference, rather than comparing January with an average that also includes summer.
The WMO Climate guide explains station identifiers, fields, like-month comparisons and CSV export. It also distinguishes the application’s processed table from the upstream source files.
Use monthly reports for questions at the monthly scale
CLIMAT observations can support a station’s monthly history. With an appropriate reference, they can also provide context for an unusually warm or wet month. They cannot reconstruct every day within that month, and one station cannot establish a global trend.
When the question concerns a storm’s timing or a hot spell’s duration, return to daily or shorter-interval observations. When it concerns long-term change, retain a documented series, review its gaps and station history, and use a suitable statistical comparison.
Data Annex
This article explains report and file definitions. It does not calculate a climate anomaly or validate a current station export against the upstream archive.
| Information to retain | Why it matters |
|---|---|
| Reporting station and month | Establishes the place and period represented |
| Variable and statistic | Distinguishes mean, total, extreme and threshold count |
| Units and source layout | Prevents applying BUFR conventions to a different text product |
| Missing-day or other completeness information | Helps assess the summary where those fields are supplied |
| Product branch and revision | Identifies the quality stage and source used |
| DWD product | Documented distinction |
|---|---|
| Raw CLIMAT tables | Public text layout with its own field definitions; limited initial checks |
| Recent monthly mean temperature | Recent years; full DWD quality control not yet completed |
| Historical monthly mean temperature | Versioned series with completed documented quality control |
Data Sources
- WMO CLIMAT conversion template: BUFR sequences, units, summary statistics and completeness fields.
- DWD raw CLIMAT product description: public text layout, variables and initial checks.
- DWD recent monthly mean-temperature description: units, yearly rows and incomplete full quality control.
- DWD historical monthly mean-temperature description: historical product format and checks.
- WMO Climate Explorer guide: monthly date labels, cards, source handling and export.