I had my test in a big snowstorm as well. Because of this the evaluator abridged the test a bit. It was a very surreal experience, I had been prepared for all of the maneuvers and instead it was mostly backing up along the curb type things.
I don’t know that it was as bad as the conditions for the OP, but at least because these are new drivers and the chances are greater for bad outcomes in conditions they don’t have many hours of experience in … I would be inclined to have tests during inclement weather postponed.
Love Mitch and Stephen - had never heard of James Acaster but took a chance based on your list and loved him :D thanks for the rec!