It would help if the controller gave incoming traffic a clear idea of how long they might have to wait.
Lets say the fog is unlikely to clear in under 30 mins so :-
You are number one, expect a delay of at least 30 minutes
You are number 10, expect a delay of at least 50 minutes
You are number 30, expect a delay of at least 90minutes.
With reasonable expectations more pilots would probably decide earlier on a diversion rather that hang around burning fuel in a futile hope of landing.