The midwinter temperature changes in the mesosphere and stratosphere are described, using conventional and satellite data. It is shown that over the northern hemisphere the so-called stratosphereic mid-winter warmings extend into the upper mesosphere. The difference between both hemispheres are pointed out. The activity of the planetary-scale waves during the last 16 northern winters and the importance of the amplification of height wave 1 before the beginning of a major warming are discussed. It is shown that during the northern winters the structure of the quasi-stationary waves shows an irregular interannual variability of the polar stratospheric temperatures. In contrast, the southern stratospheric winters are rather regular.