I’ve learned the hard way that in a city, “outdoor furniture” has to survive more than just rain. You’re dealing with UV, pollution, freeze-thaw cycles, wind tunnels between buildings, and sometimes salt off the roads, so I’d look for commercial-grade materials rather than pretty-but-fragile pieces.
For frames, powder-coated aluminum is my first recommendation. It’s light enough to move, won’t rust like steel, and handles rain and temperature swings well—just check that the coating is thick and the feet are capped or raised so water can drain. If you want metal with a heavier feel, marine-grade stainless steel, ideally 316 where salt is an issue, is excellent, but avoid cheap painted steel; it will bubble and rust at the welds.
For tabletops and seating, HDPE lumber is a very practical city choice. It doesn’t rot, splinter, or need annual sealing, and it stands up to UV and rain. Teak is another solid option if you like a warmer look: it weathers to gray and can be oiled if you prefer the honey tone, but keep up with cleaning in polluted air. Concrete or fiberglass can be great for wind resistance, though they’re heavy and less forgiving to move.
Don’t overlook the small parts: stainless hardware, drainage holes, quick-dry foam, and solution-dyed acrylic cushions. Removable covers and stackable or modular pieces make city storage much easier. I’d avoid untreated wood, cheap rattan, and MDF-core furniture.
If I were outfitting a balcony, rooftop, or courtyard, I’d start with a powder-coated aluminum frame, HDPE or teak surfaces, stainless hardware, and quick-dry cushions. Rinse it monthly, tighten bolts seasonally, and store cushions during extreme weather—and it should hold up well for years.