Changes of the thermic seasons in Warsaw in the period 1933-2004

The beginning dates and the lengths of thermic seasons in Warsaw (1951-2004) were analysed. These characteristics of seasons are very variable, especially in winter. The changes of winter length influence strongly the dates and length of adjacent seasons, that is, of early winter and early spring. The current warming is best visible exactly during these seasons: winter becomes shorter, while early winter and - to an even longer degree -early spring become longer. The period of spring, summer and autumn is characterised by grater stability. These seasons showed a very weak tendency to change on even its lack, both as regards the length and the beginning date.