Visibility forecast — how to read it

The visibility map shows forecast horizontal surface visibility in kilometres, derived from the DWD ICON-D2 model. Together with ceiling, it's what determines the GAFOR category and whether the day is legally VFR.

What the field actually is

ICON-D2 emits a diagnostic visibility field that combines relative humidity, precipitation type, and aerosol load into a single ground-level distance. It's the model's estimate of what a pilot would report as prevailing visibility — not a direct METAR measurement.

How to read the colors

• Red — below 1 km: fog / severely obscured. Not VFR.
• Orange — 1 to 5 km: haze, mist, moderate precipitation. GAFOR yellow or worse; marginal even for experienced VFR pilots.
• Yellow — 5 to 8 km: reduced visibility. Legal VFR but requires attention on landmark navigation.
• Green — above 8 km: unrestricted VFR.
• Deep green — 10 km or more: excellent — the kind of day that makes cross-country flying worth it.

When it matters most

Model caveats — fog is fast

Real-world visibility in fog can change over minutes; ICON-D2 works on a 15-minute (RUC) or hourly time step and is smoothed to the 2.1 km grid. Treat the visibility map as a heads-up that fog is likely, not a guarantee that a specific airfield will be open. For go/no-go inside 3 hours, cross-check current METARs.

Conversely, precipitation-driven low visibility (rain, snow) tends to track well — the model resolves the precipitation shield, and the visibility field follows it.