WeatherCat plugin for Indigo

Brings your weather station's live readings from WeatherCat (the macOS weather station app by Trixology) into Indigo home automation, as ordinary Indigo devices you can show on control pages, use in triggers and conditions, and log.

• One Indigo sensor device per reading: outdoor temperature, humidity, pressure, wind speed, gusts and direction, rain, dew point, wind chill, heat index, cloud base, solar, UV, soil and leaf sensors… whatever your station reports.
• Today's high and low (with the times they happened) and the change over the last hour on each reading that WeatherCat keeps statistics for.
• A Feels Like reading: heat index when it's hot, wind chill when it's cold and windy, otherwise the air temperature.
• A Station device with WeatherCat's current conditions, forecast, pressure trend, sunrise and sunset, triggered alerts and station communications status.
• Values in the units you chose in WeatherCat (°F/°C, inHg/hPa/mb, mph/km/h/knots/m/s, in/mm, feet/metres).
• Works entirely on your local network. No cloud service, account or API key.

Not affiliated with or endorsed by Trixology. WeatherCat is Trixology's product; this plugin only reads the data WeatherCat already offers to other programs.

Installing

1. Download WeatherCat.indigoPlugin (from the Indigo Plugin Store, or the latest release on GitHub, unzipped).
2. Double-click it. Indigo installs and enables it, and opens the plugin's settings.
3. Check the settings (below) and click Save.

To update later, install the new version the same way. Your devices and settings are kept.

Tip: Indigo moves a double-clicked plugin into its own Plugins folder. If you keep plugins in a folder you care about (a git checkout, say), install from a copy.

Plugin settings

Plugins > WeatherCat > Configure…

Quick start

Plugins > WeatherCat > Create Devices for All Live Readings creates, in a device folder called WeatherCat:

• a WeatherCat Station device,
• one WeatherCat Reading device for every reading your station is currently reporting (station communications counters and WeatherCat's raw rain counter are left out),
• a WeatherCat Feels Like device.

It's safe to run again: it only adds devices for readings that don't have one yet. Delete any you don't want.

Or create devices one at a time: New… > Type: WeatherCat > Model: WeatherCat Reading (or WeatherCat Station).

Reading devices

A WeatherCat Reading is an Indigo sensor device. Its value (sensorValue) is the reading in WeatherCat's units, shown with the unit, e.g. 52.6 °F, 30.42 inHg, 234° SW, 82%.

Device settings

States

Readings with statistics (WeatherCat's STAT$ items): outdoor and indoor temperature, dew point, wind chill, heat index, outdoor and indoor humidity, pressure, wind speed, 10-minute average wind speed, 1-minute wind gust, solar radiation and UV index.

Error states

Indigo shows these in the device list instead of a value:

Feels Like

Feels Like (heat index, wind chill or temperature) is a reading the plugin works out, using the US National Weather Service rule:

• Heat index when the air temperature is 80 °F (26.7 °C) or more;
• Wind chill when it's 50 °F (10 °C) or less and the wind is at least 3 mph (4.8 km/h);
• otherwise the air temperature.

It uses WeatherCat's own Calculated Heat Index, Wind Chill, Wind Speed and outdoor temperature readings. The feelsLikeSource state says which one is in use. WeatherCat's Calculated Heat Index and Wind Chill are also available as readings of their own.

Station device

One WeatherCat Station device is enough. Its display shows WeatherCat's current conditions (e.g. Overcast), or Station comms failed / WeatherCat not answering.

Its state icon is Indigo's sensor on icon when all is well, sensor tripped when station communications have failed, and sensor off when WeatherCat isn't answering.

Menu items and actions

Plugins > WeatherCat

• Create Devices for All Live Readings: see Quick start.
• Log WeatherCat Channels: lists every reading WeatherCat offers, with its current value, in the Event Log, plus WeatherCat's version and units. Handy for seeing what your station reports.
• Refresh Now: reads everything straight away.

Actions (in Action Groups, triggers and schedules: Type: WeatherCat Actions)

• Refresh All WeatherCat Devices Now.
• Put a WeatherCat Tag Into a Variable: runs any WeatherCat web tag and stores the result in an Indigo variable. This reaches anything WeatherCat can report that isn't a device, for example:

Tags are case sensitive and end in $. WeatherCat's manual (Help > WeatherCat Help, appendix 4, and the STAT$ section) lists them all.

Each Reading device also answers Indigo's Send Status Request, which refreshes all WeatherCat devices.

Units

The plugin always uses the units set in WeatherCat (WeatherCat > Preferences > Units). WeatherCat sends live values in metric, and the plugin converts them. Highs, lows and 1-hour changes come from WeatherCat already in your units, so everything matches. If you change units in WeatherCat, devices follow within one highs-and-lows interval (5 minutes by default), or straight away with Refresh Now.

Soil moisture is shown in centibars.

Rain readings

WeatherCat offers more than one kind of rain total, and they can differ:

• Precipitation Daily (Rain Today) and Precipitation Per Hour (Rain Rate) are WeatherCat's live values.
• Monthly Rain and Annual Rain come from some stations' consoles (e.g. Davis) and count from whenever the console was last reset.
• WeatherCat's own month and year totals are available with the tag action, e.g. STAT$RAIN:TOTAL:THISMONTH$. These only cover the time WeatherCat has been recording.

Troubleshooting

WeatherCat 4

WeatherCat 4 is in development (beta) at the time of writing. From its published development notes, it keeps the same RCP on port 49255 and adds new readings (lightning, voltages, particulates, a second station and more), which appear in the plugin's reading menu by themselves. It also adds an HTTPS version of RCP on port 49256, which this plugin doesn't use yet. The plugin hasn't been tested with WeatherCat 4.

How it works

The plugin polls WeatherCat's Rich Client Protocol (RCP), plain HTTP on port 49255 that answers with XML property lists:

• /discovery/channelList – the readings WeatherCat offers (asked for on every poll, because reading numbers can change);
• /data/getChannelValue/<n> – a reading's live value, in metric;
• /webtag/<tag> – WeatherCat's web tags: statistics, units, conditions, forecast, sun times;
• /discovery/systemData and /discovery/alertsList – status and alerts.

Each device remembers its reading by WeatherCat's reading type and name, not its number. That's what WeatherCat's documentation advises, since numbers can change when the station changes. docs/weathercat-rcp.md has the details and the quirks found while building this.

Development

WeatherCat.indigoPlugin/Contents/
  Info.plist                     plugin id com.5th-imperium.weathercat, version, API version
  Resources/icon.png             Plugin Store icon (drawn by tools/make_icon.swift)
  Server Plugin/
    wcrcp.py                     RCP client, unit conversion, formatting, Feels Like. No Indigo imports
    plugin.py                    the Indigo plugin
    Devices.xml, PluginConfig.xml, Actions.xml, MenuItems.xml
tests/
  test_wcrcp.py                  unit tests, and the plugin run against a fake Indigo
  fake_indigo.py                 the stand-in for Indigo's `indigo` module
fixtures/rcp/                    real WeatherCat 3.33 RCP replies; index.json maps file -> request
tools/
  capture_fixtures.py            add replies from a running WeatherCat to fixtures/rcp
  live_check.py                  run the plugin once against a running WeatherCat (no Indigo) and print every device
  make_icon.swift                draws the icon
docs/weathercat-rcp.md           notes on WeatherCat's RCP

Run the tests (no Indigo or WeatherCat needed):

python3 tests/test_wcrcp.py

Use Indigo's own Python to be sure, e.g. /Library/Frameworks/Python.framework/Versions/3.13/bin/python3 for Indigo 2025.2.

See what the plugin would make of a running WeatherCat, without touching Indigo:

python3 tools/live_check.py [host] [port]

Issues and pull requests are welcome.

Developer Notes

Integration between Weathercat and Indigo can also be done without a specific plugin using Weathercats custom web pages to output XML that an Indigo XML Plugin can just read. This just makes it easier. Yes, it was coded with help from Claude - last time I seriously coded with a Mac, it was the Metrowerks compiler: CodeWarrior and I've only dabbled since, so I'm very rusty and short on time.

Licence

Copyright © 2026 hap67 and contributors. Licensed under the GNU General Public License v3.0 or later; see LICENSE.