A temperature controller for a substrate support in a substrate processing system includes a power parameter module configured to calculate a power parameter indicative of power supplied to the substrate support. A coolant temperature parameter module configured to calculate a coolant temperature parameter indicative of a temperature of a coolant supplied to the substrate support. A heat transfer gas parameter module is configured to calculate a heat transfer gas parameter indicative of flow rates of a heat transfer gas supplied to the substrate support. A temperature calculation module is configured to calculate a temperature of the substrate support using the power parameter, the coolant temperature parameter, and the heat transfer gas parameter.