Oven appliance having a humidity sensor

An oven appliance defining a mutually-orthogonal vertical direction, lateral direction, and transverse direction, the oven appliance comprising:

• a cabinet extending along the vertical direction between a top end and a bottom end, the cabinet extending in the transverse direction from a front end to a rear end, the cabinet defining a cooking chamber and an oven vent downstream therefrom to direct an exhaust flow from the cooking chamber;
• a ventilation fan mounted to the cabinet downstream from the oven vent;
• a sensor enclosure mounted to the cabinet outside of the cooking chamber and forward from the ventilation fan, the sensor enclosure defining an enclosed volume, the sensor enclosure further defines an active flow entrance and an active flow exit in fluid communication with the enclosed volume;
• a humidity sensor disposed within the enclosed volume;
• and
• a sensor fan mounted to the sensor enclosure outside of the cooking chamber and upstream from the ventilation fan.