The studies were based on the 10-day period or monthly measurement of the sums of actual insolation from three periods of measurements: 1952-2001 - 7 IMGW (Institut of Meteorology and Water Management) meteorological stations, 1966-2000 - 6 stations and 1971-2000 - 46 stations. Variability of heliographic conditions was based on the statistical analysis of the annual, monthly and 10-day period sums from the selected meteorological stations. Coefficients of the linear trend of 10-day period and monthly insolation sums were calculated making it possible to select periods of increase or decrease in the insolation sums during a year in Poland. In order to select areas of approximate insolation conditions during vegetation a correlation matrix of insolation sums from 21 meteorological stations and a method of the cluster analysis were used. In the whole country 5 areas were selected: I - the Seaside Area, II - the Central and Western Area, III - the Area of Małopolska Upland, IV - the Eastern Area, V - the Area of the Upper Vistula and the San Rivers.