An underbody convective warming blanket includes a duct that is separate from, but in fluid communication with, interior space of the underbody convective warming blanket. The duct may be deployed to provide an air circulation conduit to shunt air around the air distribution structure in the interior space. The duct may be a flexible tube having a first end coupled to a first duct port in the underbody convective warming blanket near a first end of the underbody convective warming blanket and a second end to be coupled to a second duct port in the underbody convective warming blanket near a second end of the underbody convective warming blanket. An underbody convective warming blanket may include a midsection with an elongate columnar configuration which transitions at an end, or at each end, to a plinth-like configuration.