node-red-contrib-dwd-rainradar

A Node-RED node to access the German Weather Service (DWD) rain radar data (RADOLAN).
This node is designed to analyse current precipitation over Germany or a selected region and to provide summary values, grid data and optional image output.

⚠️ Status: Early beta.
The initial version uses a dummy implementation for development and testing.
A future release will connect to the official DWD OpenData RADOLAN products.

✨ Features

• Node-RED input node for the DWD rain radar (RADOLAN)
• Configurable area of interest:
  • Whole Germany
  • Bounding box (lat/lon)
  • Point + radius (lat/lon + km)
• Optional automatic refresh (polling in the background)
• Flexible output:
  • Summary (aggregated precipitation information)
  • Full grid data (raster)
  • Optional image placeholder (PNG/Base64, planned for a future version)
• Full editor i18n support (English / German)
• Localized help pages (English / German)
• Ready for CI/CD with GitHub Actions and npm

📦 Install

From your Node-RED user directory (typically ~/.node-red):

npm install node-red-contrib-dwd-rainradar

Or via the Node-RED Palette Manager:

1. Open the Node-RED editor
2. Menu → Manage palette
3. Tab Install
4. Search for node-red-contrib-dwd-rainradar
5. Click Install

Node: dwd-rainradar

This node appears in the input category and is labelled “DWD Rain Radar” (or „DWD-Regenradar“ when the editor language is set to German).

Configuration

Name

Optional display name.
If left empty, a default label is used.

Area mode

Defines how the area of interest is specified:

• Whole Germany
  Uses the full DWD radar domain.

• Bounding box
  Requires:

  • Min latitude
  • Max latitude
  • Min longitude
  • Max longitude
    All values are expected in decimal degrees (WGS84).

• Point + radius
  Requires:

  • Latitude
  • Longitude
  • Radius (km)

The area parameters are currently part of the configuration and are not modified by incoming messages.

Auto-refresh (sec)

Interval in seconds for automatic background updates:

• 0 → disabled (no automatic fetch)
• > 0 → fetch radar data periodically

Fetch on deploy

When enabled, the node performs an initial fetch shortly after the flow is deployed.
A full deploy (all flows) ensures that the node is re-created and the initial fetch is triggered.

Output options

Controls the structure of msg.payload:

• Summary
  Emits aggregated information about the precipitation in the area of interest.

• Full grid
  Emits a simple raster representation of the radar field (width, height, values).
  In the dummy implementation this is a small 10×10 array.

• Image (PNG/Base64)
  Reserved for future usage to provide an encoded radar image suitable for dashboards and UI templates.

Diagnostics

When enabled, the node writes additional diagnostic information to the Node-RED log, for example:

• When the node is created
• Whether fetchOnDeploy is enabled
• Auto-refresh interval
• Fetch results and errors

🔌 Inputs

Any incoming message triggers a fetch of the radar data using the current configuration.

• The content of the input message is not evaluated in the initial version.
• In a future version, optional overrides via msg.payload may be added (e.g. specific time, temporary area).

Typical usage:

• Inject node as trigger
• Timers / schedulers to trigger fetches on a custom schedule

📤 Outputs

The node sends a single message with the radar information in msg.payload.

msg.payload.meta

Metadata describing the result:

{
  "source": "DWD Rain Radar (dummy)",
  "timestamp": "2025-11-15T22:20:38.474Z",
  "mode": "de"
}

• source – source identifier (currently marked as dummy)
• timestamp – ISO 8601 timestamp when the data was created/fetched
• mode – current area mode (de, bbox, point)

msg.payload.summary

Present when Summary is enabled.

Example:

{
  "hasRain": true,
  "maxIntensity": 12.3,
  "avgIntensity": 1.7,
  "coveragePercent": 42.0
}

• hasRain – Boolean flag indicating if any rain is detected in the area
• maxIntensity – maximum intensity in the domain (dummy value in this version)
• avgIntensity – average intensity (dummy value)
• coveragePercent – percentage of cells with rain (dummy value)

msg.payload.grid

Present when Full grid is enabled.

Example (dummy):

{
  "width": 10,
  "height": 10,
  "values": [5, 0, 0, 0, ...]
}

• width / height – dimensions of the grid
• values – flattened array of raster values (length = width * height)

In the dummy implementation, every 5th cell is set to 5, the others to 0.

msg.payload.image

Present when Image (PNG/Base64) is enabled.

Example (dummy placeholder):

{
  "mimeType": "image/png",
  "data": null
}

Future versions may provide an actual Base64-encoded radar image here.

🔎 Status text

The node uses Node-RED status text to indicate its current state:

• loading… – fetching radar data
• ready – idle, waiting for input or auto-refresh
• N cells – number of cells in the last grid result (if grid output is enabled)
• error – an error occurred during fetch or processing

The text is localized according to the editor language.

🌍 Internationalisation (i18n)

This node fully supports the Node-RED i18n system.

• Editor labels and tooltips are translated via:
  • nodes/locales/en-US/dwd-rainradar.json
  • nodes/locales/de/dwd-rainradar.json
• Help text is localized via:
  • nodes/locales/en-US/dwd-rainradar.html
  • nodes/locales/de/dwd-rainradar.html
• Runtime messages and statuses use RED._() with the same namespace.

When the Node-RED editor language is changed (or set to “Browser”), the node UI and help text follow the selected language.

🧪 Example flow

A basic example flow is included in the repository under:

examples/dwd-rainradar-basic.json

This flow demonstrates:

• Triggering the DWD Rain Radar node via an Inject node
• Using “Fetch on deploy” to get data directly after deployment
• Showing the result in a Debug node

You can import it via:

1. Node-RED menu → Import
2. Clipboard
3. Paste the JSON from examples/dwd-rainradar-basic.json
4. Click Import

🗺️ Roadmap

Planned features for future releases:

• Direct integration with DWD RADOLAN OpenData endpoints
• Real precipitation intensity values (mm/h or dBZ)
• Improved grid resolution and projection handling
• Optional PNG/Base64 radar imagery output
• Additional configuration for specific RADOLAN products (e.g. RW, RY)
• Optional time selection (most recent, specific timestamp)

⚖️ License

MIT © 2025 Gerd Rütten

📝 Changelog

See CHANGELOG.md for details.

⚠️ node-red-contrib-dwd-rainradar — bringing official DWD rain radar (RADOLAN) data directly into your Node-RED flows.