The weather will naturally effect anything it come sin contact with so the motorcycle will take some decay and damage compared to that of one kept in a garage but if one can keep constant maintenance and care on the motorcycle it should be fine.
If you are careful, it should be okay. You will need to pay especially close attention to any leather (such as the seats) and treat it frequently, though.
I've owned a Suzuki for 14 years and kept it in good shape outside. Just cover it and all parts waxed, lubed and treated. Oh and yes I do live in snow country.
