A tower crane includes a tower on which is pivotally mounted a boom displaceable between a lowered position and a raised position. The crane is configurable between a service configuration in which the boom is controlled in rotation and a weather vane configuration in which the boom is in the raised position and is released in rotation on the tower to allow orientation in the direction of the wind. A wind load system is mounted on the boom and is adjustable between a retracted shape in the service configuration providing a reduced surface exposed to the wind, and a deployed shape in the weather vane configuration providing an extended surface exposed to the wind. The wind load system is configured to move from the retracted shape to the deployed shape under the effect of its own weight alone (i.e., under gravity) when the boom is raised.