We analyze the influence of changes in the frequency of circulation types on seasonal trends of eight climatic variables at 21 Czech stations in the period 1961–1998 using 24 objective and two subjective atmospheric circulation classifications from the COST733 Action. In winter, circulation changes explain around 30% of long-term linear temperature trends and around 50% of temperature changes that took place between the first and the second half of the study period.
Within-type climatic changes are responsible for a major part of the observed climatic trends in spring, summer, and autumn; but also in winter for variables other than temperature. Very high variability between results obtained using many circulation classifications suggests that such a comparative approach is crucial in synoptic-climatological studies.