I had a cat with ragged ears from frostbite that I adopted from a
shelter and we experience winters that on average would be about 25
degrees Fahrenheit at night.  All it would take is one really cold
night.  A cat's ears are so exposed and the tissue there is so thin
and sensitive and unprotected that I doubt it would take much to cause
frostbite.  Unlike human ears, a cat's ears seem cool to the touch
generally so I would speculate that the temperature of the ears is
lower than the temperature of the rest of a cat's body.  I would think
even an hour or so outside in really cold weather would damage the
vasculature of a cat's ears but I don't have any empirical evidence.
The structure seems more delicate than human ears and we can get
frostbitten ears easily on a very cold day.  It hurts just to think
about it.

No, but sometimes I think that I must be damaged for choosing to live
in a cold climate.

Because this particular cat didn't seem to have all her oars

Even if she had somehow suffered a brain injury, her babies would not
inherit an acquired  deficit.  It sounds like the cat in question is
perhaps just not as clever as some others, and maybe that includes the
ability to seek out warm hiding places.

Last winter, where I live, we have seen some lows that were marked on the
mercury, -38c, no wind at all.  I have not seen that often before (if ever).
There are strays in the little town were I work, and one of them lost both
his ears from the frost bites, but I've seen that most other cats remained
intact.  It depends on the cat's ability to survive.   I had notice that
this cat had trouble taking his share when fed.  Even if he had an abundance
of food under his nose, he acted as if he could only catch the crumbs left
by the others.  My guess is that he had some kind of illness.  I saw him
once this summer, and he was still only skin and bones..  and there was no
reason for this because there is an abundance of prey at this time of year,
and many fields are close around, its a very rural area.   So it depends on
the individual cat, his weakness or strength or health condition to start
with.   Weak is a strong word though, because that particular stray did
after all, survive the terrible winter we had last year!!

Elaine