A washing machine appliance, including methods of operation, is provided herein. The washing machine appliance may include a cabinet, a tub positioned within the cabinet, a wash basket, and a nozzle assembly. The nozzle assembly may be mounted within the cabinet and configured to provide wash fluid to the tub. The nozzle assembly may include an extendable nozzle, a valve assembly, a retractable fluid supply conduit, a supplemental heater, and a temperature sensor. The extendable nozzle may define a fluid path between a nozzle inlet and a nozzle outlet. The valve assembly may be configured to provide a flow of wash fluid to the extendable nozzle. The supplemental heater may be positioned in thermal communication with the flow of wash fluid between the valve assembly and the nozzle outlet. The temperature sensor may be positioned in thermal communication with the flow of wash fluid downstream from the valve assembly.