A methodology is demonstrated for creating responsive polymer surfaces that can alter their wetting characteristics when exposed to a humid environment. For this, we take advantage of the surface partitioning of block copolymers at the polymer/air interface and utilize a hydrophilic group at the end of the surface-active block. When exposed to water vapor, the end group, hidden below the surface when in contact with dry air, presents itself to the surface thus significantly reducing the water contact angle. This function can be reversed and repeated again and again by successive exposures of the surface to dry and wet environment, respectively.