I can't seem to get this right. : Can't put it on the
roof with the other sensors as the deliberate exposure that
the roof affords those others interferes with the accuracy
of the temperature reported.

And, mounting it on the back porch ("up" out of the way)
shades it from direct sunlight but "keeps it warm" in the
colder weather due to heat trapped by the roof of the porch
(the same roof that *shades* it from the Sun).

So, it seems like the trick is to find shade without an
"overhead covering"? (contradiction in terms??)

I'll try the porch -- but much closer to the ground (farther
from the heat-trapping ceiling)?