🌦️ meteoswiss-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.
🇩🇪 Deutsche Version
Demo query (anchor example)
How suitable is next Wednesday for the sports day at Leutschenbach school?
→ meteo_school_check(location="Zürich Oerlikon", activity="Sporttag") returns a 🟢/🟡/🔴 traffic light for each day of the coming week — straight from the MeteoSwiss ICON model.
Combined with swiss-environment-mcp:
How were air quality and weather at Leutschenbach school yesterday?
→ meteo_current(station='REH') + env_nabel_current(station='ZUE') = a complete environmental picture.
→ More use cases by audience →
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 | 🟢/🟡/🔴 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 — relevant for the client approval UI and for the LLM's safety decisions.
| Tool | readOnlyHint | destructiveHint | idempotentHint | openWorldHint |
|---|
meteo_stations | ✅ | ✗ | ✅ | ✗ (curated list) |
meteo_current | ✅ | ✗ | ✗ (live data) | ✅ (upstream STAC) |
meteo_forecast | ✅ | ✗ | ✗ (live data) | ✅ (upstream Open-Meteo) |
meteo_school_check | ✅ | ✗ | ✗ (live data) | ✅ (geocoding + forecast) |
meteo_climate_normals | ✅ | ✗ | ✅ | ✗ (embedded normals) |
meteo_warnings | ✅ | ✗ | ✗ (live data) | ✅ (opendata.swiss) |
Read rules: all 6 tools are readOnly + non-destructive — 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 → mcp[cli]>=1.0.0 |
| Update policy | Dependabot watches mcp[cli]; spec bumps are documented in the CHANGELOG with a "Tool Definition Changes" marker |
→ 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 — 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 — 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 → 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 — 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 # → {"status":"ok","service":"meteoswiss-mcp"}
On Render: "New → Blueprint" → select the repo. Defaults (plan starter, Frankfurt, single instance) are set in render.yaml.
Important: numInstances: 1 is set deliberately — 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> — 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> — 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 Zürich?
→ meteo_school_check(location="Zürich", activity="Sporttag")
What will the weather be at Leutschenbach school on Friday?
→ meteo_forecast(location="Zürich Oerlikon", days=5)
Show me current readings from the nearest MeteoSwiss station to Zürich-Schwamendingen.
→ meteo_current(station="REH")
Climate comparison
How much rain normally falls in June in Zürich?
→ meteo_climate_normals(station="KLO")
Is Lugano really much sunnier than Zürich? Show me the annual values.
→ meteo_climate_normals(station="LUG") + meteo_climate_normals(station="SMA")
Infrastructure & environment
Are there currently any weather warnings for the canton of Zürich?
→ meteo_warnings(canton="ZH")
Show me a 10-day forecast for the Heerenschürli sports facility with hourly values.
→ meteo_forecast(location="Sportanlage Heerenschürli Zürich", days=10, hourly=True)
Architecture
Claude Desktop / AI agent
│
│ MCP (stdio / Streamable HTTP)
▼
meteoswiss-mcp (FastMCP)
│
├── meteo_stations ──────────────── [embedded: ~20 SMN stations]
│
├── meteo_current ───────────────── BGDI STAC API
│ data.geo.admin.ch/api/stac/v1
│ Collection: ch.meteoschweiz.ogd-smn
│
├── meteo_forecast ──────────────── Open-Meteo
├── meteo_school_check ──────────── api.open-meteo.com/v1/meteoswiss
│ (MeteoSwiss ICON-CH1/CH2-EPS, 1–2 km)
│
├── meteo_climate_normals ───────── [embedded: normals 1991–2020]
│
└── 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) — the server cannot modify or delete any data |
| Personal data | No personal data — 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 — 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
│
├── swiss-environment-mcp Combine weather + air quality (NABEL)
│ "How were weather AND air at Leutschenbach school?"
│
└── zurich-opendata-mcp School locations → weather forecast
"Which schools in Zürich 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.
Related servers
Installation
Run via uv's uvx — 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"
]
}
}
}
