Now that the temperature outside has dropped, the windows start to accumulate water vapor. I am assuming that it might also lead to that black stuff forming. Is there a more efficient way of dealing with the condensate than wiping it dry every day?
This might be bad advice depending on the insulation of the outer walls. If you increase the insulation on these windows, the water might still condensate, but this time on your walls where you cannot see it or wipe it away. A rule of thumb is to insulate the outer walls better than the windows.