@korina Hopefully not --- Dahlem and Tempelhof were the only official (non-madis and non-pws) weather stations in Berlin.
The stations still exist, other weather sites still show data for them.

@yves70 How to get the contact information of the weather station owner? And would it be possible for windy to blacklist such stations, maybe even automatically based on the surrounding reports?

It seems that some WMO stations in Germany vanished from the windy map some days ago. For example, there is nothing anymore in the Berlin area --- in the past, there used to be at least Berlin-Dahlem, Berlin-Tempelhof and Grünow (I think the respective wmo numbers are 10381, 10384, and 10289).

Update: it's working again for me. The previously problematic system has now FF 68.0.2 running, maybe the patch level increase had helped, or maybe there was a change to the Windy page.

Any news here? I am pretty sure the problem is related to Firefox 68. Version 67 is OK.