Methodology

Where do the forecasts come from?

We don't run our own weather model. Our point forecasts are DWD MOSMIX – a statistical refinement of the ICON (DWD) and IFS (ECMWF) weather models, calibrated to the respective measuring station. For every forecast we show the model, model run, and station including distance – a forecast is valid for the station, not for your balcony.

Where does the radar come from?

The rain radar is the DWD's RADOLAN RV composite: every German radar site, 5-minute resolution, 1 km grid, including the official 2-hour short-term forecast (nowcast). We decode, project, and render the raw data ourselves. The optional satellite image is the Geocolour composite (true colour by day, infrared by night) from Meteosat (EUMETSAT), 10-minute cadence.

Austria and Switzerland

For locations in Austria and Switzerland, point forecasts come from the AROME model by GeoSphere Austria (2.5 km grid, CC BY 4.0), whose domain covers the entire Alpine region. Observations for error checking come from TAWES stations (AT) and SwissMetNet (CH), climate normals from GeoSphere and MeteoSwiss. Here too: we always show which model is behind it.

How honest is "honest"?

Every one of our forecasts is stored and later checked against the actual measurements from DWD stations: mean absolute temperature error and rain-hit accuracy, broken down by forecast horizon. The result is public under "How good are we?" – even when it looks bad.

A word on uncertainty: MOSMIX is a point forecast without an ensemble – we can't honestly derive a "spread" per forecast from it. Instead of a false sense of precision, we state our measured past error directly alongside the forecast ("recently we were off by ±x °C on average"). Genuine ensemble spreads (e.g. from ICON-EPS) are on the roadmap – but only once we can verify them just as cleanly.

We take this a few steps further: we show our error broken down by weather regime (a calm high-pressure situation is easy, scattered showers are almost a guess), compare ourselves against the simple rules of thumb "same as yesterday" (persistence) and climate normal – if we don't beat them, we say so – and make a forecast's stability visible (how much a day still shifts from run to run). And in every city's forecast check, day by day, is what we said and what was measured.

Derived values

• Balcony PV (solar): We decompose global radiation (MOSMIX Rad1h) with the Erbs model into direct and diffuse components and convert it via the sun's position onto the actual panel plane (tilt and orientation), plus ground reflection – times a performance factor of 0.85. This is more honest than flat global radiation, because a vertical balcony panel yields very differently from a horizontal surface. Default: vertical, facing south; adjustable in the app. Without horizon/shading and soiling losses – an estimate, not a yield guarantee.
• Garden: Frost risk from 2 m and soil temperature (48 h); growing degree days, base 10 °C. Spray/irrigation window = dry and low wind (< 15 km/h, against drift) and rain-free for a few hours afterward (so nothing washes off). Product-dependent – the label applies.
• Outdoors: Dry window = contiguous hours with < 0.1 mm and < 30 % chance of rain.
• Moon phase: computed from the mean synodic month – pure math, no data service. Accurate to the calendar day; sufficient for an ephemeris line.

Pollen

The DWD doesn't publish its pollen forecast per location, but for 27 forecast regions (eight species, each for today and tomorrow, in the official load levels). We don't guess which region applies to your location: we determine it via a point-in-polygon lookup against the official regional boundaries from the DWD geo services – your location gets exactly the region the DWD's own map places it in, and we name it accordingly. For locations in Austria and Switzerland, the DWD forecast covers nothing; there we honestly show no pollen data rather than a guessed one.

Climate data

Climate values per location are long-term averages 1991–2020 from the DWD Climate Data Center, each from the nearest station with a sufficient data record (max. 30 km).

Is my location covered too?

Very likely: every location with a MOSMIX station within 30 km has its own page – just type it into the search above. We deliberately leave out locations with no station nearby: a "forecast for your location" from a station 60 km away would be a lie.