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malkreide

meteoswiss-mcp

by malkreide

🌦️ meteoswiss-mcp

CI PyPI Python License: MIT swiss-public-data-mcp

MCP server for Swiss weather and climate data from MeteoSwiss.

Connects AI models to the SwissMetNet measurement network (160+ stations, 10-minute interval), MeteoSwiss ICON-CH1/CH2-EPS forecasts and climate normals 1991–2020. Part of the swiss-public-data-mcp portfolio.

πŸ‡©πŸ‡ͺ Deutsche Version


Demo query (anchor example)

How suitable is next Wednesday for the sports day at Leutschenbach school?

β†’ meteo_school_check(location="ZΓΌrich Oerlikon", activity="Sporttag") returns a 🟒/🟑/πŸ”΄ traffic light for each day of the coming week β€” straight from the MeteoSwiss ICON model.

Combined with swiss-environment-mcp:

How were air quality and weather at Leutschenbach school yesterday?

β†’ meteo_current(station='REH') + env_nabel_current(station='ZUE') = a complete environmental picture. β†’ More use cases by audience β†’


Related MCP server: Open-Meteo MCP Server

Tools (6)

Tool

Description

Data source

meteo_stations

List SwissMetNet stations (filterable by canton)

Embedded

meteo_current

Current 10-min observations for a station

BGDI STAC API

meteo_forecast

1–16 day forecast for a place or coordinates

Open-Meteo / MeteoSwiss ICON

meteo_school_check

🟒/🟑/πŸ”΄ traffic light for outdoor school events

Open-Meteo / MeteoSwiss ICON

meteo_climate_normals

Monthly climate normals 1991–2020

Embedded (KLO, SMA, BER, LUG, GVE)

meteo_warnings

Current weather warnings & links

opendata.swiss + links

Tool annotations (MCP hints)

All tools carry explicit MCP annotations β€” relevant for the client approval UI and for the LLM's safety decisions.

Tool

readOnlyHint

destructiveHint

idempotentHint

openWorldHint

meteo_stations

βœ…

βœ—

βœ…

βœ— (curated list)

meteo_current

βœ…

βœ—

βœ— (live data)

βœ… (upstream STAC)

meteo_forecast

βœ…

βœ—

βœ— (live data)

βœ… (upstream Open-Meteo)

meteo_school_check

βœ…

βœ—

βœ— (live data)

βœ… (geocoding + forecast)

meteo_climate_normals

βœ…

βœ—

βœ…

βœ— (embedded normals)

meteo_warnings

βœ…

βœ—

βœ— (live data)

βœ… (opendata.swiss)

Read rules: all 6 tools are readOnly + non-destructive β€” the server fundamentally cannot write or delete anything. idempotentHint=False marks tools that return different values depending on when they are called.

MCP protocol version

Aspect

Value

Tested spec versions

2024-11-05, 2025-03-26, 2025-06-18 (via the mcp[cli] SDK)

FastMCP SDK version

see pyproject.toml β†’ mcp[cli]>=1.0.0

Update policy

Dependabot watches mcp[cli]; spec bumps are documented in the CHANGELOG with a "Tool Definition Changes" marker

β†’ Full roadmap & update strategy: docs/roadmap.md


Quick start

Claude Desktop

{
  "mcpServers": {
    "meteoswiss": {
      "command": "uvx",
      "args": ["meteoswiss-mcp"]
    }
  }
}

Claude Desktop (local development)

{
  "mcpServers": {
    "meteoswiss": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/meteoswiss-mcp", "meteoswiss-mcp"]
    }
  }
}

Cloud / Render.com (Streamable HTTP)

Configuration via ENV variables (the CLI flags --http / --port N still work as an override):

Variable

Default

Meaning

MCP_TRANSPORT

stdio

stdio or streamable-http

MCP_HOST

127.0.0.1

Bind address β€” never change locally

MCP_PORT

8000

Port

MCP_ALLOW_ANY_HOST

unset

Must be set to 1 to allow the server to bind to 0.0.0.0 (containers/cloud only)

MCP_LOG_LEVEL

INFO

DEBUG / INFO / WARNING / ERROR β€” structured JSON logs on stderr

MCP_ALLOWED_ORIGINS

unset

Comma-separated list of allowed origins for CORS. Empty = CORS disabled (same-origin only). Mcp-Session-Id is exposed automatically.

MCP_API_KEY

unset

If set: every request except /health requires X-API-Key: <key> or Authorization: Bearer <key>. Constant-time comparison.

MCP_STATELESS_HTTP

0

1 enables FastMCP stateless mode β†’ each HTTP request opens a new session. Prerequisite for multi-replica deploys without sticky sessions (SCALE-002/003).

OTEL_EXPORTER_OTLP_ENDPOINT

unset

If set + pip install meteoswiss-mcp[otel]: OpenTelemetry spans per tool call + automatic httpx instrumentation are sent as OTLP-HTTP to the collector.

OTEL_SERVICE_NAME

meteoswiss_mcp

Service name in the OTel resources

MCP_CACHE_ENABLED

1

0 disables the TTL cache entirely (e.g. for end-to-end tests)

MCP_CACHE_TTL_STAC

300

TTL in seconds for STAC SMN observations (default 5 min)

MCP_CACHE_TTL_OPEN_METEO

600

TTL for ICON forecasts (default 10 min)

MCP_CACHE_TTL_GEOCODING

3600

TTL for geocoding lookups (default 1 h)

MCP_CACHE_TTL_OPENDATA

3600

TTL for the opendata.swiss catalogue (default 1 h)

MCP_CACHE_TTL_WARNINGS

300

TTL for the structured warnings API (default 5 min)

MCP_CLIMATE_NORMALS_PATH

unset

Path to a JSON file with additional climate normals β€” see data/climate-normals.example.json

MCP_WARNINGS_API_URL

unset

URL of a structured MeteoSwiss warnings API. The host must be on the egress allow-list. Schema-tolerant (GeoJSON features, a warnings array or items).

MCP_CLIMATE_NORMALS_URL_TEMPLATE

unset

URL template for runtime lookup of climate normals (for stations without embedded or JSON values). Tokens: {station} (lowercase), {STATION} (uppercase), {param} (MeteoSwiss code tre200m0/rre150m0/sre000m0). Example: https://data.geo.admin.ch/.../{station}/{param}.txt. The host must be on the egress allow-list.

# Local test (safe, loopback only)
MCP_TRANSPORT=streamable-http meteoswiss-mcp

# Container / Render
MCP_TRANSPORT=streamable-http MCP_HOST=0.0.0.0 MCP_ALLOW_ANY_HOST=1 meteoswiss-mcp

Docker / Render

The repo includes a production-ready multi-stage Dockerfile (non-root user, HEALTHCHECK) and a render.yaml blueprint:

# Build + test locally
docker build -t meteoswiss-mcp .
docker run --rm -p 8000:8000 meteoswiss-mcp
curl http://127.0.0.1:8000/health   # β†’ {"status":"ok","service":"meteoswiss-mcp"}

On Render: "New β†’ Blueprint" β†’ select the repo. Defaults (plan starter, Frankfurt, single instance) are set in render.yaml.

Important: numInstances: 1 is set deliberately β€” sticky-session routing for multi-replica (audit SCALE-002/003) is not yet implemented.

Structured logging

All tool invocations, upstream failures and egress blocks are emitted as JSON events on stderr (stdio-transport safe). Example:

{"tool": "meteo_forecast", "days": 7, "has_coords": false, "event": "tool_invoked", "level": "info", "timestamp": "2026-05-20T07:00:00Z"}
{"tool": "meteo_forecast", "endpoint": "geocoding", "error_type": "HTTPStatusError", "event": "upstream_failed", "level": "warning", "timestamp": "..."}
{"url": "https://evil.example.com/", "method": "GET", "reason": "host not in allow-list", "event": "egress_blocked", "level": "warning", "timestamp": "..."}

HTTP-mode security

  • MCP_HOST deliberately defaults to 127.0.0.1 so that --http on a dev laptop is not accidentally exposed to the local subnet (audit finding SEC-016).

  • All outgoing HTTP calls (including redirect follows) are validated against an allow-list: data.geo.admin.ch, api.open-meteo.com, geocoding-api.open-meteo.com, opendata.swiss. Other hosts and IP literals (in particular 169.254.169.254, RFC1918) are rejected with EgressBlocked (SEC-004 / SEC-021).

  • CORS: disabled by default (same-origin only). Browser clients (e.g. claude.ai web) need MCP_ALLOWED_ORIGINS=<csv> β€” the Mcp-Session-Id header is then automatically in Access-Control-Expose-Headers (SDK-004).

  • API-key auth: disabled by default. In a production HTTP setup, always set MCP_API_KEY=<random> β€” requests without a valid X-API-Key or Authorization: Bearer … are rejected with 401 (SEC-009 / SEC-013). /health stays open for container health probes.

Example: production HTTP stack

# 32 bytes of randomness as the auth key
export MCP_API_KEY=$(python -c "import secrets; print(secrets.token_urlsafe(32))")

MCP_TRANSPORT=streamable-http \
MCP_HOST=0.0.0.0 \
MCP_ALLOW_ANY_HOST=1 \
MCP_ALLOWED_ORIGINS=https://app.example.com \
MCP_API_KEY="$MCP_API_KEY" \
meteoswiss-mcp

Example queries

School planning

Which days next week are suitable for a sports day in ZΓΌrich?
β†’ meteo_school_check(location="ZΓΌrich", activity="Sporttag")

What will the weather be at Leutschenbach school on Friday?
β†’ meteo_forecast(location="ZΓΌrich Oerlikon", days=5)

Show me current readings from the nearest MeteoSwiss station to ZΓΌrich-Schwamendingen.
β†’ meteo_current(station="REH")

Climate comparison

How much rain normally falls in June in ZΓΌrich?
β†’ meteo_climate_normals(station="KLO")

Is Lugano really much sunnier than ZΓΌrich? Show me the annual values.
β†’ meteo_climate_normals(station="LUG") + meteo_climate_normals(station="SMA")

Infrastructure & environment

Are there currently any weather warnings for the canton of ZΓΌrich?
β†’ meteo_warnings(canton="ZH")

Show me a 10-day forecast for the HeerenschΓΌrli sports facility with hourly values.
β†’ meteo_forecast(location="Sportanlage HeerenschΓΌrli ZΓΌrich", days=10, hourly=True)

Architecture

Claude Desktop / AI agent
        β”‚
        β”‚ MCP (stdio / Streamable HTTP)
        β–Ό
meteoswiss-mcp (FastMCP)
        β”‚
        β”œβ”€β”€ meteo_stations ──────────────── [embedded: ~20 SMN stations]
        β”‚
        β”œβ”€β”€ meteo_current ───────────────── BGDI STAC API
        β”‚                                   data.geo.admin.ch/api/stac/v1
        β”‚                                   Collection: ch.meteoschweiz.ogd-smn
        β”‚
        β”œβ”€β”€ meteo_forecast ──────────────── Open-Meteo
        β”œβ”€β”€ meteo_school_check ──────────── api.open-meteo.com/v1/meteoswiss
        β”‚                                   (MeteoSwiss ICON-CH1/CH2-EPS, 1–2 km)
        β”‚
        β”œβ”€β”€ meteo_climate_normals ───────── [embedded: normals 1991–2020]
        β”‚
        └── meteo_warnings ──────────────── opendata.swiss CKAN + links

Data sources

Source

URL

License

BGDI STAC API (MeteoSwiss OGD)

data.geo.admin.ch/api/stac/v1

CC BY 4.0

Open-Meteo (MeteoSwiss ICON)

api.open-meteo.com/v1/meteoswiss

CC BY 4.0

Open-Meteo Geocoding

geocoding-api.open-meteo.com

CC BY 4.0

opendata.swiss CKAN

opendata.swiss/api/3/action

CC BY 4.0


Safety & limits

Aspect

Details

Access

Read-only (readOnlyHint: true on all tools) β€” the server cannot modify or delete any data

Personal data

No personal data β€” all sources are aggregated, publicly available open data

Rate limits

Built-in per-query caps: max 50 results per API call, 30 s timeout

Authentication

No API keys required β€” all data sources are publicly accessible

Licenses

All data under CC BY 4.0 (MeteoSwiss Open Government Data)

Terms of Service

Subject to the ToS of the respective data sources: MeteoSwiss OGD, Open-Meteo, opendata.swiss


Known limitations

ID

Tool

Description

BUG-01

meteo_current

STAC asset structure can vary per station; fallback to a direct link is implemented

LIM-01

meteo_climate_normals

Only 5 stations embedded (KLO, SMA, BER, LUG, GVE); the rest via an opendata.swiss link

LIM-02

meteo_warnings

A direct warnings REST API is planned from Q2 2026 (MeteoSwiss OGD phase 2); currently links + CAP

LIM-03

meteo_current

Shows 10-min values in UTC; no automatic conversion to local time


Portfolio synergies

meteoswiss-mcp
    β”‚
    β”œβ”€β”€ swiss-environment-mcp   Combine weather + air quality (NABEL)
    β”‚                           "How were weather AND air at Leutschenbach school?"
    β”‚
    └── zurich-opendata-mcp     School locations β†’ weather forecast
                                "Which schools in ZΓΌrich have sports-day weather?"

Testing

# Unit tests (no network)
PYTHONPATH=src pytest tests/ -m "not live" -v

# Live tests (real APIs)
PYTHONPATH=src pytest tests/ -m live -v

# Linting
ruff check src/ tests/

Development

git clone https://github.com/malkreide/meteoswiss-mcp
cd meteoswiss-mcp
pip install -e ".[dev]"

MCP Inspector (local test)

PYTHONPATH=src npx @modelcontextprotocol/inspector python -m meteoswiss_mcp.server

Contributing & Security


License

MIT License – see LICENSE.

Source data: MeteoSwiss Open Government Data (CC BY 4.0). When using the data, cite: Source: MeteoSwiss.


swiss-environment-mcp zurich-opendata-mcp swiss-transport-mcp

Installation

Run via uv's uvx β€” no clone or manual install needed. Add to your MCP client config (mcpServers for Claude Desktop, Cursor and Windsurf; use a top-level servers key for VS Code in .vscode/mcp.json):

{
  "mcpServers": {
    "meteoswiss-mcp": {
      "command": "uvx",
      "args": [
        "meteoswiss-mcp"
      ]
    }
  }
}
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Maintenance

–Maintainers
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2wRelease cycle
4Releases (12mo)
Commit activity

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