Mesoscale variations of the rotational temperature of excited hydroxyl (OH*) are studied at altitudes 85 – 90 km using the data of spectral measurements of nightglow emission at Russian observatories Zvenigorod (56 ° N, 37°E.) in years 2004 – 2016, Tory (52 ° N, 103°E) in 2012 – 2017 and Maimaga (63° N, 130° E) in 2014 - 2019. The filtering of mesoscale variations was made by calculations of the di�erences between the measured values of OH* rotational temperature separated with time intervals of dt~ 0.5 - 2 hr. Comparisons of monthly variances of the temperature di�erences for various dt allow us to estimate coherent and non-coherent in time components of the mesoscale temperature perturbations. The �rst component can be associated with mesoscale waves near the mesopause. The non-coherent component may be produced by instrument errors and atmospheric turbulence. The results allow us correcting the observed mesoscale temperature variances at all listed sites for contributions of instrumental and turbulent errors. Seasonal and interannual changes in the coherent component of mesoscale variances of the temperature at the observational sites are studied, which may re�ect respective changes in the intensity of mesoscale internal gravity waves in the mesosphere and lower thermosphere region.