Weather Station Core (ws_core)

Know the exact minute the rain starts - and what your weather station was trying to tell you.

ws_core turns the plain temperature, wind, and rain sensors you already have in Home Assistant into a full weather intelligence system. Its headline trick, when you enable Precipitation Nowcast, is watching your own rain gauge and correcting the forecast against it, so you get a live countdown to the minute rain begins.

🌧️ sensor.ws_minutes_until_rain → 7 min

The 50+ core sensors run entirely on your machine, computed from your own station data. No cloud, no API keys, nothing leaves your network. Optional extras (precipitation nowcast, air quality, forecast blending) add cloud enrichment only when you switch them on.

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🚀 Try this one thing first

Never get caught in the rain. Point ws_core at your rain gauge, enable Precipitation Nowcast during setup (or later under Configure → Features), then watch sensor.ws_minutes_until_rain and have Home Assistant announce before the first drop. For simpler rain-rate or probability alerts, the Rain Start Warning blueprint sets up notifications in under a minute.

Once you are hooked, here is the rest:

• Stop the sprinklers precisely. Calculates real Evapotranspiration (ET0) so your smart irrigation knows exactly how much water the lawn actually needs.
• Forecast with the internet off. The offline Zambretti forecast predicts the next 12 hours from your local barometric pressure trend alone.
• Automate your home around the weather. 10 ready-to-use blueprints: TTS rain alerts, freeze warnings, irrigation skips, lightning safety, and high-wind awning retraction.
• ...and 170+ derived sensors in total covering comfort, fire danger, solar, soil, and data quality once you enable the optional feature packs (see the nerd section).

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📡 Does it work with my station?

If your station is in Home Assistant, it works with ws_core.

Works well with:

Station / source	How ws_core uses it
Ecowitt / Ambient Weather	GW-series, WS90, WH57 lightning, rain, wind, solar, UV and indoor sensors already exposed in HA
WeatherFlow Tempest	Temperature, humidity, pressure, wind, rain, UV, illuminance and lightning entities
Davis Instruments	WeatherLink entities for classic PWS measurements and Davis comfort indices
Netatmo	Outdoor module plus optional rain and wind modules
MQTT / REST / template-backed sensors	Any standard HA sensor entities with temperature, humidity, pressure, wind and rain

All you need are standard sensors like temperature, humidity, pressure, wind, and cumulative rain. The Hardware Mapping Guide shows the usual entity patterns.

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⚡ The 60-Second Quickstart

Install via HACS (Recommended)

1. Open HACS in your Home Assistant sidebar.
2. Go to Integrations → ⋮ → Custom repositories.
3. Add https://github.com/kmich/ha_ws_core as an Integration.
4. Search for "Weather Station Core", install, and restart Home Assistant.

Configure

Go to Settings → Devices & Services → Add Integration and search for "Weather Station Core". The setup wizard asks you to map 7 basic sensors:

• Temperature, Humidity, Absolute Pressure, Wind Speed, Wind Gust, Wind Direction, Rain Total

That's it! After the wizard completes, 50+ derived sensors appear automatically. Enable additional features like fire danger or nowcasting via the Configure button on the integration.

Not sure what to automate first? Start with the Use Cases: rain alerts, irrigation skips, awning protection, frost warnings, and air-quality actions.

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📊 The "Wow" Dashboards

ws_core comes with drop-in, premium Lovelace dashboards for your data.

Mobile View	Desktop View

Check out the dashboards/ directory for the YAML code. We provide:

• A vanilla dashboard using only native HA cards.
• An enhanced dashboard using popular custom cards (mini-graph-card, mushroom).
• Ready-to-use gauge presets with sensible severity color bands.

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🤖 Top Automations

Don't reinvent the wheel. We've included import-ready blueprints to automate your home based on your local weather:

• Rain Start Warning: Announce over TTS or send a push notification when rain is expected in the next few minutes.
• Freeze Warning: Trigger actions when the temperature drops below freezing.
• High Wind Gusts: Automatically retract your awnings or close the blinds when a high gust is recorded.
• Heat Stress / UTCI: Notify when outdoor conditions become dangerous for work or exercise.
• Poor Air Quality: Close the windows and turn on the air purifiers when PM2.5 spikes.

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🔬 Advanced Features (The "Nerd" Section)

Behind the scenes, ws_core implements rigorous meteorological and scientific algorithms to derive the most accurate insights from your station's data:

• UTCI & WBGT: The gold-standard heat-stress indices used by the WHO.
• Three Fire Danger Systems: Canadian FWI, Australian McArthur FFDI, and US Fosberg FFWI.
• Stull Wet Bulb & Buck Frost Point: Precise derivations with ice-constant handling.
• Nowcast Ground-Truth Blending: Combines Open-Meteo 15-minute grids with your live rain gauge data (70% local / 30% NWP) for the best short-term prediction.
• Network Uploads: Syncs to 8 networks simultaneously (WUnderground, Weathercloud, PWSWeather, WOW, AWEKAS, CWOP, OWM, Windy).
• Adaptive Rain Probability: Learns over a rolling 90-day window whether the local heuristics or the NWP forecasts have been more accurate.
• Localized UI & Sensors: The setup wizard (including the hemisphere and climate-region pickers) and the human-readable sensors (conditions summary, alert message, frost risk) follow your Home Assistant language, with English, French, German, Spanish, Italian, Dutch, Polish, and Portuguese built in.

For the math, citations, and formulas behind these features, read the Scientific Documentation.

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🤔 Why not just use template sensors?

You can absolutely hand-roll a heat-index template or install Thermal Comfort. The difference is scope and correctness:

	A few template sensors	Thermal Comfort	ws_core
Comfort indices (heat index, wind chill, dew point)	Manual	✅	✅
Rain-start countdown from your own gauge	❌	❌	✅
Evapotranspiration (ET0) for irrigation	❌	❌	✅
Offline pressure-trend forecast	❌	❌	✅
Fire danger, UTCI/WBGT, frost point	❌	❌	✅
Ready-made automation blueprints	❌	❌	✅ (10)
Runs fully local	✅	✅	✅ (core)

Already on Thermal Comfort? There is a step-by-step migration guide that keeps your history.

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🔒 Data & Privacy

ws_core is local-first. All core derived sensors are computed on your machine from your own station data and never leave your network. Every feature that sends data to a third party is opt-in and disabled by default, so nothing is transmitted until you turn it on in Configure → Features.

When you enable them, the following optional features contact external services:

Feature	Destination	Data sent
Forecast (Open-Meteo, Met.no, NWS, OWM, Pirate Weather, Météo France, HA entity)	The selected provider	Your coordinates
Precipitation nowcast, air quality, pollen, sea temperature, solar forecast	Open-Meteo / forecast.solar	Your coordinates
French Vigilance / Vigicrues	Météo-France public APIs	Your department / nearest station
Network uploads (WUnderground, Weathercloud, PWSWeather, WOW, AWEKAS, CWOP, OWM, Windy)	Each network you enable	Your live observations and that network's credentials
MQTT republishing	Your own MQTT broker	Derived sensor values

API keys and passwords you enter are stored in the Home Assistant config entry. The diagnostics export redacts all credentials and coordinates, so it is safe to attach to a bug report.

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❓ FAQ & Troubleshooting

• Why are my entities unavailable? Ensure your source sensors are online. If a required sensor (like temperature) is unavailable, dependent derived metrics will gracefully become unavailable until the source recovers.
• Which sensors do I select during setup? If Auto-Discovery didn't find your station, read our Hardware Mapping Guide for exactly which Ecowitt, Tempest, or Netatmo entities to select.
• How do I migrate from the Thermal Comfort integration? We have a dedicated migration guide with step-by-step instructions.
• Do I need an API Key? No. All core features run completely offline locally. Optional features like Air Quality or Nowcast use free APIs that require no registration.
• Which fire-danger number should I trust? Use the one calibrated for your region: FFDI (sensor.ws_ffdi) in Australia and New Zealand, FWI (sensor.ws_fwi, Canadian system) elsewhere, and FFWI (sensor.ws_ffwi) as a US/global cross-check. sensor.ws_fire_risk_score is a simplified 1-10 display value. None of these is an official warning - always defer to your local fire authority.
• Which ET0 should I use for irrigation? If you have mapped a solar-radiation sensor, prefer sensor.ws_et0_pm_daily (FAO-56 Penman-Monteith, the reference method). Without solar radiation, use sensor.ws_et0_daily (Hargreaves-Samani, ±15-20%).
• How do I uninstall? Go to Settings → Devices & Services → Weather Station Core → ⋮ → Delete. This removes the integration, its device, and all derived entities and their history. To remove the code as well, delete the repository from HACS → Integrations. Any dashboards or blueprints you imported are independent and can be removed separately.

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