Abstract: A fluid warming device for an extracorporeal blood treatment apparatus, comprises: an outlet temperature sensor (31) operatively active at an outlet (22) of a fluid warming path (23) to detect a measured outlet temperature (To) of a fluid leaving the fluid warming device (18); an electronic control unit (29) operatively connected to the outlet temperature sensor (31). The electronic control unit (29) is configured to perform the following procedure: receiving, from the outlet temperature sensor (31) a signal correlated to a measured outlet temperature (To); correcting the measured outlet temperature (To) through a correction model to obtain an actual fluid outlet temperature (Tout); adjusting a heating power (Ph) of heating elements to keep the actual fluid outlet temperature (Tout) at a set reference temperature value (Tset).