Habital planets are also dependent on what kind of plant life can be grown..
and such.. Length of growing season (that is if you want something more than
VAT food, argh, Id ratehr eat an MRE for  along period of time).

I know in Fairbanks (Furbanks to some) the winter can get to -60 or so F, but
in the summer can get to +90 and such.. I know of worse places..
       
Incans and Sherpa and other low pressure atmosphere and such are a limit in
human adaptability(someone mentioend that Incan woman must come to lower
elevations to have babies brought to term? true?) I remember a book by
Pourrnelle I think that delt with a planet was lower density air..

I wonder what the limit on the other end of atmospheres?

I am limiting to human needs and stresses and not alien possibilties..
Thou aliens might be more adapted to a totally alien to human environment, such
as the upper atmosphere of Jupiter or??

Almost makes bio-engineered life easy...