@fedecandela
Do you think the weather models like IFS from ECMWF or GFS from NCEP « are not giving accurate weather anymore » ?
However these global models with a grid spacing (resolution) of respectively 9km and 22km are sometime not able to provide a high accuracy in some local conditions.
About Fog, this layer is provided by ICON model from the German weather services. This is rather experimental. You better rely on Sounding forecast (right click on mouse or Skew T in plugin list on desktop), and of course, on METAR/TAF shown when selecting Airports.
https://community.windy.com/topic/14733/fog-forecast?_=1615968537678
On the other hand, conditions during a flight can be provided by Route planner (right click on mouse):
Capture d’écran 2021-03-17 à 09.27.12.png