Observation

Overview

CHMI’s open-data portal provides access to historical climate observations from the Czech Hydrometeorological Institute’s station network across Czechia at 10-minute, hourly, daily, monthly and annual resolution. No API key or registration is required — the portal is fully public.

Station metadata comes from metadata/meta1.csv. A station whose sensor was relocated appears under several operational periods; these are collapsed to a single station using the most recent position for the coordinates and the full extent for the operational dates. The catalogue does not expose a region, so state is always null, and a station’s end_date is null while it is still active.

Observations are addressed per station and element. The daily, monthly and annual resolutions store one flat CSV per station/element (e.g. dly-<WSI>-T.csv); the 10_minutes and hourly resolutions store one CSV per station/element/month under a year sub-directory, so they require a date range. The 10-minute and hourly files only reach back to 2018.

The daily files may hold several time functions — the daily mean (AVG) alongside fixed-term readings — so the appropriate one is selected per parameter and timestamps are normalised to the calendar day. The monthly/annual files additionally carry an aggregation function, so the climatological mean of daily means/maxima/minima is used for temperature and the total for precipitation.

Not every station measures every parameter — a station/parameter combination that CHMI doesn’t have simply contributes no rows.

License

Data is © Czech Hydrometeorological Institute (CHMI). See CHMI open data for further information and usage conditions.