A housing 6 is provided for a wind sensor 2. A sensing element 4 is mounted in the housing 6 to measure the speed of the passing fluid flow, and the housing 6 comprises at least one surface 40, 42 having shaped surface elements 38, such as protrusions from and/or indentations in the surface 40, 42, for inducing turbulence in fluid flowing across the surface 40, 42. The turbulence caused by the shaped surface elements 38 results in the speed measured by the wind sensor 2 being less affected by uncontrolled transitions between laminar and turbulent airflow, and thus enables more accurate calibration of the wind sensor 2.