Kinetic temperatures determined from the line profiles of the 17,924-K (5577 ¿) emission of atomic oxygen in the night sky for nearly a solar cycle show considerable variation. In this investigation we have established the existence of solar and magnetic activity modulation of atmospheric temperature at the height of emission of this line as well as the presence of significant variations with 5-, 2.5-, 1-, and 0.5-year periods. The secular variations of 5- and 2.5-year periods have not been previously observed at the height of emission, although the 2.5-year period variation can be identified with the stratospheric quasi-biennial oscillation. The annual and semiannual variations are in agreement with measurements by other means, thus showing the height of emission to be rather constant and corroborating the results obtained with satellites. No statistically significant variation in the behavior of the temperature with 30¿ of longitude separation at 40 ¿N latitude is found. The temperature is found to follow the following equation: T=231(¿3)-0.46(¿0.03) ?216+0.16(¿0.03) F-2 +0.34(¿0.05) Ap-4 +7.1(¿0.8) cos[2&pgr; (y-1963.31(¿0.07))/5> +6.0(¿0.7) cos[4&pgr; (y-1965.87(¿0.04))/5> +7.3(¿0.7) cos[2&pgr; (d+2(¿5))/365.25> +2.4(¿0.6) cos[4&pgr; (d-9(¿30))/365.25> where ?216 and F-2 are the 10.7-cm solar radio noise averaged over 216 days and lagged by 2 days, respectively; Ap-4 is the planetary magnetic index lagged by 4 days, y is the date, and d is the day number beginning with January 1. The standard deviations of the determined coefficients are indicated in parentheses. A correlation coefficient of 0.915 is found between the above expression and the data, with a significance better 1%. The statistically estimated standard deviation of fit is 6.5 ¿K.