The best way to match fog color with Sky shader example?

I am building a scene based on Sky object included in Three.js.

and I am trying to dynamically apply fog colour corresponding to Sky object’s ground colour. However, since Sky object uses shader material I am not sure how to extract the color value from it. I was looking up if it is possible to export the pixel values of the fragment shader then send them to the Scene object.

Any ideas? I appreciate your help!