A microwave appliance, as provided herein, may include a cabinet, a door, and an air handler. The cabinet may extend in a lateral direction between a first side end and a second side end. The door may be movably mounted to the cabinet at the first side end or the second side end to move between an open position permitting access to a cooking chamber and a closed position restricting access to the cooking chamber. The door may include a peripheral frame and a front window bounded by the peripheral frame. The peripheral frame may define an air inlet and an air outlet downstream from the air inlet. The air outlet may be defined below the front window. The air handler may be mounted within the door in fluid communication between the air inlet and the air outlet to motivate an airflow therethrough.