We present a study of the long-term variations of the near-ground pressure fields in winter inferred from NCAR/NCEP reanalysis data for middle and high latitudes of the northern hemisphere, responsible for the variations of monthly mean temperatures in Eastern Siberia. We suggest a new classification scheme to be used for Arctic pressure fields, which well reflects the influence of circulation processes on the near-ground temperature variations in Siberia. In the long-term variations of temperature, mean pressure fields, and frequency of occurrence of circulation types, one can quite clearly see the quasi-decadal variations, associated with the dynamics of Icelandic and Aleutian Lows.