We carried out the analysis of the power spectrum of the time series of the daily mean values of the surface air temperature in Saratov city (Russia) in the time interval from 1945 through 1999. In the power spectrum are discovered two tidal harmonics, the harmonic with the period of synodic month, connected with a change in the insolation during the motion of system the Earth – Moon around the common center of masses, and also harmonic, which corresponds to the average period of rotation of the active regions of the Sun.
