The short answer is that it depends on the bench. A well-made outdoor park bench using galvanized steel, aluminum, or properly powder-coated steel is designed to survive all four seasons without developing serious rust. A cheap bench made from untreated or thinly painted mild steel can absolutely start rusting after one winter, especially if it sits in snow, slush, or road salt.
Why does a bench rust after just one winter? Steel rusts when moisture and oxygen meet the metal. Winter is harder on outdoor furniture because freeze-thaw cycles open tiny cracks in paint, salt speeds up corrosion, and benches sitting in melting snow stay damp for weeks. If the frame is hollow and water gets trapped inside, it can rust from the inside out even when the outside looks fine. That is why many low-cost steel benches fail early.
The material and finish matter more than whether the frame is called metal. Galvanized steel gets dipped in molten zinc, and that zinc coating protects the steel even if the surface is scratched. A powder-coated steel bench is also a good choice when the coating is applied over a primer or e-coat, because the finish seals out moisture. Aluminum is naturally rust-resistant, so it will not develop the same red rust as steel, though it can form a dull oxide layer. Stainless steel is even more forgiving, but lower grades can still show surface staining near salt water. Wood and recycled plastic benches do not rust in the frame, but their bolts and hardware should still be stainless or coated.
So are these park benches made to withstand all four seasons, or will they start rusting after one winter? If the product description calls out galvanized steel, powder-coated steel, aluminum, stainless hardware, or weather-resistant construction, the bench should handle all four seasons. If the listing only says “steel frame” with no mention of coating, drainage, or weather protection, I would expect rust sooner rather than later. There is no perfectly rust-proof park bench, but a quality weather-resistant park bench is not going to be ruined by one normal winter.
To make any all-season park bench last longer, keep it from sitting in puddles, clean off leaves and slush, and touch up deep scratches with matching paint or clear touch-up. In snowy areas, avoid shoveling salty snow directly against the legs. A little maintenance goes a long way, but the real difference is buying the right material in the first place.