Meteologix AG / Kachelmannwetter published their “smart-home” API which now includes quite a few parameters for previously defined locations. https://www.business.meteologix.com/api
full docs are at kachelmannwetter.com - Public API
I could setup a json sensor in the YAML or maybe even program an integration. one core question for me is how does HA handle “forecast” sensor values such as “rain within the next 3h” or “wind gusts tomorrow” ?
By the way: I would be very interested in an integration. 
I think they do it like the DWD.
In the documentation, there are the “Advanced Parameters”. There you can find the forecast in 1, 3 or 6 hour intervals. Look here:
https://api.kachelmannwetter.com/v02/_doc.html#/operations/get_forecast_advanced
So I guess you only get the “complete” data for the selected period.
Or have I misunderstood your question?
Jens
“@EdTonic@norden.social” (Mastodon)
has done a Rest-Sensor and a template:
Rest:
Template:
The original thread (in German):
Maybe it will help you.
Jens