Multitude of meteorological parameters defines weather and it continuously oscillates around the average climate values. Although patterns repeat after a certain period, nevertheless they virtually are never identical with preceding cases. They have different intensity, duration and consequence. However, some lawfulness of repetitiveness of patterns and meteorological parameters were observed and they can be described and defined by the indices of circulation. In this paper, we analyze the repetitiveness of hot and cold summers in Belgrade, which are defined by temperature and number of days with maximum temperature above a certain value. The analysis is focused on a very hot summer, which poses a potential threat due to rainfall and drought deficit, and favorable conditions for forest fires. By spectral and graphical method we observed lawfulness of their repetitiveness and on the base of that we made we made projections of temperature regime. The result indicates that in the next 30-35 years the number of days with the maximum daily temperature equal to or greater than 35°C decreases and in the equally long time again increases. Because the temperature correlates with the number of days with the maximum daily temperature, the average summer temperature should have an oscillation of about 65 years like trend of the number of days.