Weather Sources

weNow aggregates data from multiple weather providers simultaneously and computes a consensus forecast. This page documents the active and disabled sources, how ensemble aggregation works, and how confidence is communicated to users.

Active Sources

Disabled Sources

The following providers are integrated but currently disabled, pending API key fixes:

• AccuWeather
• WeatherBit
• Tomorrow.io

Ensemble Aggregation

Rather than relying on a single weather provider, weNow combines data from all active sources into a consensus forecast. Here is how it works:

1. Parallel fetching -- The backend sends requests to all active weather APIs simultaneously using Promise.allSettled. If one or more sources fail, the remaining sources still produce a valid result.
2. Normalization -- Each API adapter converts its raw response into the shared WeatherData interface. All temperatures are normalized to Celsius and all wind speeds to meters per second, regardless of the source format.
3. Weighted median -- The backend computes a weighted median across all successful responses. Sources are weighted by forecast model quality: ECMWF-based sources (such as Open-Meteo) receive the highest weight, followed by GFS-based sources (such as OpenWeatherMap), then blended model sources (such as WeatherAPI and Visual Crossing).
4. Outlier removal -- Values that diverge significantly from the group consensus are excluded from the final median calculation, reducing the impact of erroneous readings from any single provider.

Confidence Indicators

weNow displays a color-coded confidence badge on weather cards and widgets to indicate how closely the sources agree:

Forecast Data

The ensemble aggregation extends beyond current conditions into forecast periods:

• Daily forecast -- Up to 7 days of forecast data, computed by applying the weighted median across each provider's daily predictions.
• Hourly forecast -- Up to 48 hours of forecast data, computed similarly from each provider's hourly predictions. Returned only when the client opts in via includeHourly: true, and used by widgets in hourly forecast mode.

Unit Normalization

All weather API adapters normalize their responses to a consistent set of units before ensemble aggregation occurs:

• Temperature -- Always stored and transmitted in degrees Celsius, regardless of whether the upstream API returns Fahrenheit or Kelvin.
• Wind speed -- Always stored and transmitted in meters per second (m/s), regardless of whether the upstream API returns km/h, mph, or knots.

This normalization happens at the adapter level so that all downstream logic -- median calculation, outlier removal, and client display -- operates on a single, consistent unit system.