Hello, first of all, thank you for your interest. �� Our product is water-repellent thanks to the membrane layer located between the fabric and the lining. However, as with any fabric, the membrane layer has a limited water-saturation capacity. Water-repellency may decrease during prolonged and heavy rainfall. Allowing the product to air dry for a while helps the fabric dry out again, which helps maintain its performance. This is not unique to our product but can also be observed in other textile products that use membrane technology. Thank you for your understanding. ��