Whether your outdoor furniture can be left in the rain depends primarily on its construction material. True all-weather materials like powder-coated aluminum, teak, and high-quality synthetic resin wicker are designed to withstand rain and sun exposure. However, even these benefit from occasional covers during harsh weather or long winter months to prevent accelerated wear, mildew, or water pooling.
For furniture made of steel (unless stainless), iron, or standard wood, a waterproof cover is necessary to prevent rust, rot, and damage. Cushions and fabrics, even if labeled "weather-resistant," should be stored or covered during rain, as they can retain moisture leading to mold.
Best practice is to check the manufacturer's care instructions. Using furniture covers, storing cushions, and performing seasonal cleaning will significantly extend the life and appearance of your outdoor investment, ensuring your patio remains a welcoming space for years.