nc
What is a .nc file?
application/x-netcdf
NetCDF (.nc, Network Common Data Form) is a binary, self-describing format for array-oriented scientific data. It stores multidimensional variables (like temperature over latitude, longitude, and time) with named dimensions, units, and metadata attributes, and is a standard in climate, ocean, and geoscience.
How to use a .nc file
Use an example .nc file to test NetCDF readers (netCDF4, xarray, Panoply), CF-convention validators, and gridded-data pipelines, or to verify dimension and variable extraction.
Download example .nc files
- NetCDF Gridded Data (.nc)A NetCDF-3 (classic) file holding a small CF-convention gridded temperature field over latitude, longitude, and time, with named dimensions and units — for testing NetCDF readers like netCDF4 and xarray.
- NetCDF CF-1.8 Gridded Air Temperature (.nc)A NetCDF-3 classic file holding a 4x5x6 air-temperature field with full CF-1.8 coordinate metadata: standard names, axis attributes, units on every variable, and a declared _FillValue. Use it to check that a reader attaches units and coordinates to the array rather than returning bare numbers.
- NetCDF Packed int16 with scale_factor / add_offset (.nc)The same temperature field stored as int16 and recovered through the CF packing attributes scale_factor and add_offset. This is the failure that parses cleanly and is silently wrong: a reader that ignores the attributes returns values around -2000 instead of 260-292 K.
- NetCDF Time Axes — Epochs, Units and Calendars (.nc)Three CF time coordinates over the same six records: hours from the Unix epoch, days from 2026-01-01, and the same days under a 365_day calendar. A decoder that assumes one epoch, or ignores the calendar attribute, dates the records wrongly without raising anything.
- NetCDF Unlimited Record Dimension (.nc)A NetCDF-3 file with a genuine unlimited record dimension, so the record variable is stored interleaved rather than contiguously while the fixed-size station variable is not. It exercises the striding path that a reader written only against fixed dimensions gets wrong.
- NetCDF 64-bit Offset Format — CDF-2 (.nc)The same 4x5x6 temperature grid written in the 64-bit offset variant of NetCDF-3, whose only visible difference from the classic file is the fourth magic byte and the width of the header offsets. Use it to check that format sniffing looks at the version byte instead of stopping at the 'CDF' signature.
- NetCDF _FillValue, missing_value and NaN Together (.nc)One variable that hides absent data three different ways at once: two _FillValue cells, one legacy missing_value cell and one raw NaN, with valid_min and valid_max also declared. Averaging the raw array without honouring all three gives roughly -60 K instead of a real mean.
- NetCDF Multi-Variable Station File — Four Unit Systems (.nc)Four physical quantities on one shared (time, station) grid, each with its own CF units string including the dimensionless '1' and the UDUNITS 'm s-1' spelling. It is the fixture for a unit-aware layer that has to keep four different unit systems straight in a single file.
and 1 more in the library.