The question of whether outdoor furniture can be left exposed to rain depends largely on the materials it's constructed from. Modern outdoor furniture comes in various materials with different levels of weather resistance, making some better suited for rain exposure than others.
Metal furniture, particularly aluminum and stainless steel, generally handles rain well due to their rust-resistant properties. However, iron furniture, unless specifically treated for weather resistance, will rust when consistently exposed to moisture and requires protective covers or indoor storage during rainy seasons.
Wood furniture presents a mixed scenario. Teak and other dense hardwoods naturally withstand moisture and develop a attractive silver-gray patina over time. Softer woods like pine require regular sealing and benefit greatly from covers when not in use. Synthetic materials including resin wicker, plastic, and polywood excel in wet conditions, as they're specifically designed to resist water damage, mold, and fading.
While many contemporary outdoor furniture pieces are marketed as weather-resistant, consistent rain exposure will accelerate wear on all materials. Cushions and fabrics particularly need protection, as trapped moisture can lead to mold and mildew growth. For furniture longevity, using covers during extended rainy periods or offseason storage is recommended, even for weather-resistant pieces. Regular cleaning and proper maintenance will significantly extend your outdoor furniture's lifespan, regardless of material.
Ultimately, while some furniture can technically survive rain exposure, protective covers provide an extra layer of defense that preserves appearance and structural integrity over time. Consider your local climate, material type, and maintenance commitment when deciding whether to cover your outdoor furniture.