 Located in the Białystok Uplands ( Polish : <unk> Białostocka ) of the Podlaskie Plain ( Polish : <unk> <unk> ) on the banks of the Biała River , Białystok ranks second in terms of population density , eleventh in population , and thirteenth in area , of the cities of Poland . It has historically attracted migrants from elsewhere in Poland and beyond , particularly from Central and Eastern Europe . This is facilitated by the fact that the nearby border with Belarus is also the eastern border of the European Union , as well as the Schengen Area . The city and its adjacent municipalities constitute Metropolitan Białystok . The city has a Warm Summer Continental climate , characterized by warm summers and long frosty winters . Forests are an important part of Białystok 's character , and occupy around 1 @,@ 756 ha ( 4 @,@ 340 acres ) ( 17 @.@ 2 % of the administrative area of the city ) which places it as the fifth most forested city in Poland . 
