Agios Stefanos Weather Station, Attica

Forecast source

The choice applies to widgets, maps and forecasts. Actual station readings stay unchanged. Automatic tries Open-Meteo first, then available direct sources if a supported request fails.

Open-Meteo

Data service providing forecasts from NOAA, ECMWF, ECCC, DWD, the Met Office, Météo-France and JMA. Available models, variables and grids depend on the location and product.

Direct model sources

XIONIA collects data directly from the model providers. Forecasts and maps are served after the source cycle has been published and collected. The selected product shows its model, resolution, available variables and run.

How models combine

Each available family contributes once per variable. Direct forecasts select the freshest available GFS grid and use equal family weights as the baseline. Local weights apply only where enabled after validation. The comparison shows actual percentages and model cycles.

Additional model forecasts are also shown for comparison and backtesting. Their presence does not automatically add weight to the combined forecast; check the displayed weights.

Coverage and missing values

A dash means unavailable data. Wind and gust may use different models. AIGFS temperature is excluded when it cannot be compared on the same elevation basis. Six-hour precipitation is water equivalent, not snow depth.

Time window

A “Today” label with hours in parentheses covers only the stated time window; subsequent days require full local coverage. Days 8–14 are a less certain outlook. Agreement between models is not a probability from a true ensemble.

Ensemble forecasts

Ensemble systems provide multiple forecast scenarios; the available systems appear in the chart selector and image catalogue. AIGFS is the single forecast; AIGEFS is the separate ensemble. Available variables and forecast horizons differ by system.