The article deals with the problem of using a mathematical model of the three-dimensional non-stationary temperature field to calculate the strength of concrete, the hardening in winter conditions. There is data on the developed mathematical model describing the processes of heat exchange based on the differential equation of heat conduction. The boundary conditions of the III - kind: the heat exchange of a solid with the ambient air, and the IV - kind: the condition of the thermal junction of two solids have been modeled. The realization of the model with the numerical method of heat balances has been proposed. The analysis of advantages and disadvantages of the classical method based on the regular cooling has been conducted. The comparison of the data produced as a result of the calculation through the classical method and the data obtained by the calculation based on the mathematical modeling has been carried out. The conclusion on the effectiveness of using the mathematical modeling to predict the strength of concrete incubating in winter conditions has been made.