The geographical location and surface features are the two most important factors determining the climate of Poland. Due to the location of Poland in the temperate latitudes, Arctic air masses dominate. The share of maritime air is greater than of continental air (46% to 38%), because of the more common, western (oceanic) circulation of air. The pattern of terrain forms along the parallels of latitude also aids the flow of humid air masses from the ocean to Poland (75% of atmospheric fronts come from the West).

The transitional, maritime-continental nature of the climate of Poland causes large day-to-day and year-to-year variability in the weather patterns. The features of the continental climate are more prevalent in the southeast, which is reflected in the increase of the amplitude of average annual air temperature, as well as in the change of distribution of precipitation during the year. The spatial distribution of air temperatures in Poland is affected by the altitude and the distance from the Baltic Sea and from the Atlantic Ocean. Both of these properties are visible in the distribution of the average annual temperatures. The lowest average temperatures are in the mountains (Tatra Mountains, Sudetes and Swietokrzyskie Mountains) and in the heights in the Pomeranian and Masurian Lake District. The highest average temperatures are in the western and central lowlands (Silesian Lowland, Kujawy) (MAP illustrating mean annual temperatures). In January the latitudinal pattern of isotherms shows a significant increase of continental features to the east (the average monthly temperature varies from -1 ^oC in the west to -4.5 ^oC in the east and -5.5 ^oC in the area of Suwalki). The July latitudinal pattern of isotherms shows that the Baltic Sea has a cooling effect on northern Poland (16.5^oC on the coast and 18-19^oC in the south).

The amount of precipitation depends on the shape and exposition of the terrain. This is why the largest annual precipitation totals are in the mountains and the highlands (more than 600 mm), while in the lowland parts of Poland the totals are lowest (450–550 mm). The highest totals of precipitation fall on slopes facing prevailing winds. For example, the Pomeranian and Masurian Lake Districts located in the north of the country (about 600 mm) and the highest parts of the Sudetes and Carpathian Mountains (over 1200 mm). In the Sudetes, there is more precipitation than in the Carpathian Mountains due to stronger oceanic influences. In turn, the coast of the Baltic Sea receives a smaller amount of precipitation than the lake districts to the south because there are no factors forcing convection (the rise of the of air masses) and, as a result – precipitation. The Gdansk Bay (laying in a precipitation shadow) also receives less precipitation than the terrain to the west of it (MAP illustrating mean annual precipitation). The annual totals of precipitation vary a lot from year to year (up to 250% in particular months). In the course of a year summer precipitation is higher than winter: twice as high in the northwestern parts of Poland and four times as high in the southeast. Another indication of the continental nature of Poland's climate is the dominance of spring precipitation over autumn in the east, while in the west it is the opposite.

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