Recent observations of a seasonal oscillation in the time of occurrence of the thermospheric midnight temperature maximum suggest that even at low latitudes (<20¿) there is a latitudinal (seasonal) variation in the amplitudes and phases of the higher-order tidal modes. Temperature data from the Atmosphere Explorer E Neutral Atmosphere Temperature Experiment have been used to investigate this question, obtaining the temperature as a function of local time at two mean latitudes: -17.5¿ and 17.5¿. The altitude range covered is 250--400 km. The 24-hour temperature functions are obtained during the same time of the year in both hemispheres, and they show the midnight temperature maximum occurring earlier in the summer hemisphere than in the winter hemisphere. In addition, the daytime summer temperature variation is characterized by a gradual rise toward the afternoon maximum followed by a rapid decrease into the night, whereas the winter variation shows a rapid increase toward the afternoon maximum followed by a gradual decrease into midnight. Tidal analysis of the temperature function shows that the observed variations can be accounted for by the first three tidal harmonics, each harmonic showing a latitudinal (seasonal) variation. The most significant variation is observed in the semidiurnal component, which is always dominant in the winter hemisphere and therefore accounts for most of the winter nighttime temperature maximum. The terdiurnal component is as strong as the semidiurnal one in the summer hemisphere but is negligible in winter. The equinoxes are characterized by symmetric excitation of the tidal components with respect to the equator, with the semidiurnal larger than the terdiurnal. We interpret the latitudinal solstice variation of the semidiurnal component as a superposition of the semidiurnal tide induced by ion drag and the semidiurnal component excited by the EUV source. In summer the duration of the EUV source exceeds 12 hours, and the sign (phase) of the semidiurnal source component opposes that of the ion drag-induced component. In winter, the source duration is less than 12 hours, and the phases of these two components are of the same sign, enforcing each other, thus producing the larger semidiurnal component observed.