Unfortunately, not all UV umbrellas can be used in the rain, only the ones that are marketed as “water repellent” or “waterproof.” Sun umbrellas marketed as “water resistant” may not hold up in a downpour. For rain protection, you want to select a UV umbrella that has a hydrophobic coating, like Teflon or polyurethane, that will cause the water to roll off without seeping into the fabric.