If it's moisture/temperature related, it would mean that the Impreza isn't well made.
Last night, we had family for a party.
I did a small survey.
Everybody live in my region, so moisture/temperature should affect their car too.
Nissan Versa 2010, Mazda 3 2012, Mazda 3 2008, Toyota Matrix 2011.
None had any problem!