An apparatus for assessing ablation size as a function of temperature information associated with an energy applicator includes the initial step of positioning an energy applicator in tissue. The energy applicator includes a radiating section and a temperature sensor. The radiating section is operably coupled to an energy source. The apparatus delivers energy from the energy source through the radiating section to tissue. The apparatus causes cessation of energy delivery through the radiating section to tissue for a predetermined time interval, monitors the temperature sensor for at least a portion of the predetermined time interval to obtain temperature information associated with the energy applicator during the at least a portion of the predetermined time interval, and evaluates the temperature information to assess ablation size.
