We searched for a weather data provider with acceptable quality, privacy policy and affordable cost (aCalendar is free/one-time-paid, so recurring costs coming from a 3rd party service are a big problem).

Unfortunately, there was not a single provider fulfilling our requirements. 

We recommend to use a dedicated weather app.

Alternatively you can subscribe to the local weather forecast in Google Calendar (add p#weather@group.v.calendar.google.com online in a desktop browser) but it might be that Google removes this sometime soon, as it is no longer offered to add from the user interface.

Similarly you can add sunrise/sunset times as p#sunrise@group.v.calendar.google.com in your Google Calendar.