A refrigerator appliance includes a cabinet that defines a chilled chamber. The cabinet has a duct with an inlet and an outlet. The inlet and outlet of the duct is contiguous with the chilled chamber of the cabinet such that air within the chilled chamber is flowable into the duct at the inlet of the duct and air within the duct is flowable into the chilled chamber at the outlet of the duct. A heat pump system is operable to cool the chilled chamber of the cabinet. The heat pump system includes a cold side heat exchanger in thermal communication with the air within the duct. The heat pump system also includes features for condensing water vapor from the air within the duct prior to the cold side heat exchanger.