A general analysis of solar radio fluxes between 1000 and 10,000 Mc/s has been made for an entire solar cycle. It is shown that a correlation between a solar radio-flux index and the temperature of the thermopause can be found in the range of 8–10 cm if its basic component is associated with a 27-day mean value. A linear correlation is found between the 27-day mean value of the 8-cm radio flux and the thermopause temperature. However, there is a departure from linearity at 10.7 cm for fluxes of less than 150 units. The oscillation during a so-called 27-day period has a value that is about 50 per cent that of basic component. It is shown that no corpuscular effect is needed in addition to the normal heating of the thermosphere by ultraviolet radiation. A table is given to deduce tha relationships between radio fluxes at 8 and 10 cm and average nighttime and daytime temperatures. Finally, the maximum, mean, and minimum temperatures have been deduced for nighttime and daytime conditions between 1952 and 1962.