Apparatus and methods described herein provide for boundary layer flow sensor and corresponding determination of the flow characteristics of an ambient airflow over an aerodynamic surface. According to one aspect of the disclosure provided herein, the boundary layer flow sensor includes a body configured for mounting within or below the aerodynamic surface, a pressure port configurable between an open state for taking pressure measurements within the boundary layer of the ambient airflow and a closed state that protects the pressure port from contaminants when not in use.