Outdoor Furniture Covers

Yes and no, or little. Keep furniture covered when not in use for extended periods of time to keep the furniture clean and dry, reducing cleaning time and helps reduce oxidation.

Forgive me if I'm wrong, but I do not think true stainless steel oxidizes. Perhaps you have another type of metal furniture outdoors??

The moisture will gather under a waterproof cover with condensation. Your best bet would be to bring the furniture pieces of wood furniture or place on a solid surface (deck, concrete, pavers, etc.) before covering any type of coverage. In this way, the air will be able to move around furniture to keep it dry.

Good Luck