I am in northern Minnesota. A timber that has been recommended to me recently as fairly rot resistant is Eastern Larch, called tamarack locally. I have also come across a canadian web site, name slips my mind, that claimed its furniture, made from the stuff, is quite weather resistant.
I am about to put up a small wood shed I cut from the stuff, and hope to see some proof in the pudding. It will check and twist on you -- Get that thing cut and together quick!
does anybody else have any experience with eastern tamarack as a weather worthy wood?