Forecast Providers¶

Weather Station Core supports seven interchangeable forecast backends. Change provider at any time via Settings → Devices & Services → Weather Station Core → Configure → Forecast without reinstalling.

sensor.ws_forecast_provider shows the currently active provider.

Provider comparison¶

Provider	Free	API key	Coverage	Notes
Open-Meteo (default)	Yes	No	Global	No registration required
Met.no	Yes	No	Global (excellent Europe)	Norwegian Meteorological Institute
NWS / NOAA	Yes	No	US only	Returns error outside continental US
OpenWeatherMap	Free tier	Yes	Global	One Call 3.0 API; free tier requires registration at openweathermap.org
Pirate Weather	Free tier	Yes	Global	Dark Sky-compatible API; free tier at pirateweather.net
Météo France	Free tier	Yes	Global	Météo Concept API; free tier at api.meteo-concept.com
HA weather entity	Yes	No	Depends on entity	Uses any existing `weather.*` entity in HA

Open-Meteo (default)¶

Global hourly and daily forecast. No account, no API key. Updated every 15 minutes.

Supports the nowcast feature (sensor.ws_minutes_until_rain) — this is a separate Open-Meteo endpoint that works regardless of which provider you choose for the 7-day forecast.

Met.no¶

Norwegian Meteorological Institute's public API. Particularly accurate for Northern Europe, the Nordic region, and polar areas. No API key or registration required. Requires a valid contact email in the User-Agent header (automatically set by ws_core).

NWS / NOAA¶

US National Weather Service forecast API. No API key required. Returns an error if your coordinates are outside the continental United States.

OpenWeatherMap¶

Uses the One Call 3.0 API endpoint. A free tier is available but requires registration at openweathermap.org to obtain an API key. Enter the key in Configure → Forecast.

Pirate Weather¶

A Dark Sky-compatible API hosted at pirateweather.net. Free tier available; API key required. Suitable as a fallback for users who had Dark Sky access.

Météo France¶

Uses the Météo Concept API (api.meteo-concept.com). Free tier available; API key required. Contributed by @Benjamin45590.

Home Assistant weather entity¶

Uses any existing weather.* entity already integrated into Home Assistant. No external network call is made — forecast data comes from the existing HA integration.

This is useful if you already have Met.no, OpenWeatherMap, or another HA weather integration set up and do not want ws_core to make its own API calls.

To configure: in Configure → Forecast, select "Home Assistant weather entity" as the provider, then pick the entity from the dropdown.

Uses the weather.get_forecasts service (HA 2024.2+) with fallback to the forecast attribute on older installations.

How ws_core combines sources¶

There is a single active forecast provider at a time (the one you select). ws_core does not silently fail over to a different provider, so the source of every forecast value is always predictable and shown in sensor.ws_forecast_provider. The provider result is cached and refreshed on a fixed cadence (about every 15 minutes); if a refresh fails, the last good forecast is retained and the forecast sensors stay available rather than dropping to unknown.

Local station data and the provider forecast are combined in three explicit places, in this order of trust for the near term:

Nowcast (0-2 hours): your live rain gauge is blended with the Open-Meteo 15-minute grid (a tapering 70 / 40 / 10 % local weight over the first three hours), because your own gauge is the ground truth for what is happening right now.
Rain probability: a local barometric/wind heuristic is blended with the provider precipitation probability. When at least ten verified outcomes exist, the blend weight is learned from each source's rolling 90-day Brier score; otherwise a fixed time-of-day weight is used.
Forecast agreement: sensor.ws_forecast_agreement compares the local Zambretti outlook against the provider probability and reports aligned / diverging / conflict, so a disagreement is surfaced rather than hidden.

Beyond the first few hours, the selected provider's forecast is used as-is.

Adding a new provider¶

See Contributing for the provider contribution path.

New providers require: a Python file in custom_components/ws_core/providers/, a one-line registry entry in providers/__init__.py, and translation strings for the provider name.