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foehn

MeteoSwiss Open Data — Python API, CLI and MCP server.
Tabular data as Polars DataFrames and Parquet, gridded data as xarray and Zarr.

foehn downloads every MeteoSwiss OGD collection through the STAC API, converts station CSVs to Parquet with Polars, and opens gridded collections — NetCDF climate grids, GRIB2 forecasts and ODIM radar composites — as xarray Datasets or Zarr stores. It can ingest everything into Databricks Delta tables on a schedule, and ships an MCP server so LLMs can query Swiss weather data directly.

Highlights

  • 20+ collections, one interface — weather stations, pollen, radar, hail maps, forecasts, climate grids and scenarios.
  • Tabular and gridded — CSV station data as DataFrames or Parquet; NetCDF, GRIB2 and radar as xarray Datasets or Zarr stores.
  • Incremental by default — only files that changed since the last run are downloaded, tracked per dataset and time slice.
  • Scriptable CLI — every command prints a table for people and CSV/JSON for pipelines, with diagnostics kept on stderr.
  • MCP server for LLMs — give any MCP client live access to MeteoSwiss data.
  • No Spark required — download and conversion use Polars only; Spark is optional, for Delta ingestion.

Installation

pip install foehn                 # or: uv add foehn
pip install "foehn[grids]"        # xarray + Zarr for NetCDF, GRIB2 and radar
pip install "foehn[mcp]"          # the MCP server
pip install "foehn[databricks]"   # PySpark + Delta ingestion

foehn requires Python 3.11 or later.

Quick start

import foehn

# Recent daily observations for Bern, as a Polars DataFrame
df = foehn.load("smn", station="BER", frequency="d")

# What does each column mean?
foehn.parameters("smn")

# One radar composite as an xarray Dataset (needs foehn[grids])
ds = foehn.open_dataset("radar_precip", match="cpcYYDDDHHMM")

foehn list                                         # every dataset
foehn load smn --station BER --frequency d         # preview in the terminal
foehn load smn --station BER --frequency d -o ber.parquet
foehn download smn pollen                          # to ./data/meteoswiss as Parquet

{
  "mcpServers": {
    "foehn": { "command": "foehn", "args": ["mcp"] }
  }
}

Where next
Collections Every MeteoSwiss dataset, its categories and time slices
Python API guide Loading data, metadata, downloading and Parquet conversion
Gridded data NetCDF, GRIB2 and radar as xarray Datasets and Zarr stores
Command line Every subcommand, flag, output format and exit status
MCP server Setup, configuration and the available tools
Databricks pipeline The Declarative Automation Bundle
API reference Every public function, generated from the docstrings

Data sources

Data is provided by MeteoSwiss Open Government Data through the geo.admin.ch STAC API. foehn is an independent project and is not affiliated with MeteoSwiss.