Whether you can leave your urban outdoor furniture outside all winter depends heavily on three key factors: the material it's made from, the specific climate you live in, and the quality of its protective finish.
For true all-weather materials like powder-coated aluminum, certain treated metals, and high-quality synthetic resins (e.g., polywood or synthetic rattan), leaving them outside is generally acceptable. These materials are engineered to resist moisture, rust, and UV damage. However, even these benefit from simple protective measures. Using fitted covers is highly recommended to prevent the accumulation of moisture, dirt, and debris in crevices, which can lead to mildew or staining. For chairs with cushions, always store those indoors, as they will absorb moisture and be ruined.
Conversely, furniture made from natural materials like untreated wood, iron (which can rust), or wicker should never be left exposed to winter elements. Freeze-thaw cycles, snow, and rain will cause irreversible damage like warping, cracking, and corrosion. This type of furniture must be cleaned, dried, and stored in a dry, protected place like a garage or shed.
The local climate is also a major consideration. A mild, dry winter poses far less risk than a season with heavy snow, ice, and prolonged freezing temperatures. In harsh climates, even all-weather furniture will have a longer lifespan if it is stored.
In summary, you can leave all-weather furniture outside with the aid of protective covers, but you must store non-all-weather materials and cushions indoors. When in doubt, consult the manufacturer’s care instructions for the best advice on preserving your investment.