The short answer is: it depends heavily on the material. While it's generally not recommended, some all-weather furniture can survive with proper preparation. Leaving most furniture exposed to snow, ice, and freeze-thaw cycles leads to premature damage. Wood can warp, crack, and rot. Metal may rust, especially if coatings chip. Cushions trap moisture, leading to mold and mildew.
However, high-quality all-weather wicker (PE resin), powder-coated aluminum, and certain treated teak woods have better resistance. For these, thorough cleaning and using protective covers are essential. For all other materials like steel, iron, standard wood, and fabric cushions, the clear advice is to store them indoors or in a dry shed for winter.
To minimize damage if you must leave furniture out, ensure it is completely clean and dry before the first frost, elevate it off wet ground, use waterproof covers designed for breathability, and secure covers against wind. Remember, even "weather-resistant" furniture benefits from winter protection to extend its lifespan and appearance.