Forecast or present weather data sometimes include a weather code according to the WMO code table 4677 and 4680. There are also measuring instruments available that provide those codes (Ott Hydromet and Thies Clima, for example).
To display appropriate icons to that weather codes I created a searchlist extension, that can be used with all skins. It is part of the
weewx-DWD extension, that is not restricted to DWD data any more but more general and can retrieve data from several governmental weather services.