Pirin National Park was inscribed on the World Heritage List in 1983. The high mountain peaks and crags of Pirin are the remains of an old Miocene peneplain. The mountain ridges are generally of early Pliocene age but in some localities between 1,200m-1,600m are of old Pliocene age. The denudation of the area occurred more widely during the Quaternary period when the snow cover descended to 2,200m-2,300m. There are many rivers and waterfalls.
Summer is cool and short.
C. Mean annual temperature at lower altitudes is 14 C and less than 2 C at higher levels. Rainfall varies from 550-60mm at low altitude to 1100mm or more at higher altitudes. The presence of limestone rocks, the southerly position of the range and close proximity to the Aegean, coupled with its relative isolation, have made Pirin Mountain an important refuge. Forests in the park are mainly coniferous with endemic Macedonian pine Pinus peuce being widespread and forming the treeline in the granite part of the mountain. Endemic Bossnian pine Pinus heldreichii occurs in the highest zone of the karst area.