The method of digital difference filters has been applied to the analysis of OH and O2 rotational temperature obtained with airglow temperature photometers installed at Rikubetsu (43.5°N, 143.8°E), Shigaraki (34.8°N, 136.1°E), and Sata (31.0°N, 130.7°E) in Japan. These nightglow observations cover the time interval of 2010–2018 at altitudes between 85 and 90 km. Seasonal variations in the monthly standard deviation of rotational temperature perturbations with periods of 0.7–8 h, which may be partly associated with internal gravity waves (IGWs) in the mesopause region, have been studied. Near the mesopause, seasonal variations in the relative standard deviation of the rotational temperature have maxima, the strength and timing of which depend on the location of the observing site and on the type of nighttime emission. These differences can be caused by differences in the activity of wave sources and conditions of wave propagation, differences in heights of different emission layers and seasonal changes in the complex system of photochemical processes for OH and O2 nightglows.