In reply to mountain.martin:
I have stored, and continue to do so, books, clothes and other belongings under a veranda, exposed to temperature change but protected from water, for almost a decade. Nothing damaged so far.
I packed the stuff away in summer (dry air, dry belongings) into bin bags, inside cardboard boxes which themselves were sealed, air tight, in two bin bags each. The whole stack is on pallets and under a tarp. A royal pain when I need to get something out.
The ideas you have and that others have shared seem just as workable. Clean, dry, protected is the key.