ArtP wrote:
It is also my understanding that the level of icing encountered is
more complicated than a linear relationship to temperature so that
temperatures near freezing don't necessarily imply less accumulation
than lower temperatures.

In fact, just the opposite. The worst icing happens when it's just a
little below freezing, as super-cooled droplets freeze on contact with
the airplane. As you get much colder, 1) there's less total water in
the air, and 2) what's there will already be frozen, so it mostly
bounces off instead of sticking.