The invention relates to a temperature distribution determining apparatus for determining a temperature distribution within an object caused by applying energy to the object. A temperature distribution measuring unit (6, 7) measures a spatially and temporally dependent first temperature distribution in the object (3), while the energy is applied to the object (3) such that the object (3) is heated to a temperature within a first temperature range, and a temperature distribution estimating unit (5) estimates a spatially and temporally dependent second temperature distribution in the object (3) within a second temperature range, which is different to the first temperature range, based on the spatial and temporal dependence of the measured first temperature distribution. Since temperature distributions can be obtained not only in the first temperature range, but also in the second temperature range, the overall temperature range, in which the temperature distribution can be determined, can be increased.
