Integral parameters of reactor fuel pins are usually measured after long periods of irradiation, where each period can extend over a number of irradiation cycles. Examples of these parameters include cladding diametral strain and parameters involved in the evaluation of fuel/cladding chemical interaction and fuel restructuring. Analysis of these parameters requires knowledge of calculated irradiation parameters, which can vary between irradiation cycles and within the cycles. Irradiation temperature is one such parameter. A calculated weighted average temperature that takes into account the fluctuations in temperature between irradiation cycles is introduced. The work discusses the justification for using this temperature and a methodology for its validation. The methodology is based on comparing calculated average temperatures with temperatures inferred from the postirradiation examination of restructured binary metallic fuel pins in the Experimental Breeder Reactor II. The analysis shows reasonable agreement between the two temperatures. The peak irradiation temperatures, which are usually used in the analysis, were out of the range of the temperatures inferred from the experimental observations, showing the importance of using the average temperature.