page_title: Pirin
section_title: Climate
hierarchical_section_title: Pirin / Climate
caption_attribution_description: Български: Пирин, Пирин This is a photo of a natural heritage site in Bulgaria, id: NP01
context_page_description: The Pirin Mountains are a mountain range in southwestern Bulgaria, with Vihren at an altitude of 2,914 m being the highest peak. One hypothesis is the mountain was named after Perun, the highest god of the Slavic pantheon and the god of thunder and lightning. Another version is that the etymology of the range derives from the Thracian word Perinthos, meaning "Rocky Mountain".
  The range extends about 80 km from the north-west to the south-east and is about 40 km wide, spanning a territory of 2,585 km². To the north Pirin is separated from Bulgaria's highest mountain range, the Rila Mountain, by the Predel saddle, while to the south it reaches the Slavyanka Mountain. To the west is located the valley of the river Struma and to the east the valley of the river Mesta separates it from the Rhodope Mountains. Pirin is dotted with more than a hundred glacial lakes and is also the home of Europe's southernmost glaciers, Snezhnika and Banski Suhodol.
  The northern part of the range, which is also the highest one, is protected by the Pirin National Park, declared a UNESCO World Heritage Site in 1983.
context_section_description: Pirin is situated within the continental Mediterranean climate zone and due to its altitude the higher sectors have Alpine climate. The climate is influenced by Mediterranean cyclones mainly in late autumn and in winter, bringing frequent and high rainfall, and by the Azores anticyclone in summer, making the summer months hot and dry. The relief has a crucial influence on the climate. Pirin has three altitude climate zones — low between 600 and 1000 m, middle between 1000 and 1800 m and high above 1800 m. The low altitude zone is heavily influenced by the Mediterranean climate, the influence being more pronounced on the western slopes facing the Struma valley than on the eastern slopes along the Mesta valley. The high altitude zone is characterised by low temperature, low temperature amplitude, many cloudy days, lasting and thick snow cover, strong winds and intensive sun radiation.
  Winters are cold and prolonged while summers are cool and short. The temperature decreases with the altitude, which is more visible in summer. The mean annual temperature is around 9–10 °C in the low, 5–7 °C in the middle and 2–3 °C in the high altitude zone. The coldest month is January with average temperature varying between −5 and −2 °C. The hottest month is July with temperature averaging 20 °C at 1600 m and 15 °C at 2000 m. Temperature inversions, i.e. increase in temperature with height, are observed in 75% of the winter days.
  The annual precipitation in Pirin is 600–700 mm in the lower zones and 1000–1200 mm in the higher. The rainfall occurs mostly in winter and spring, while summer is driest season. The air humidity is 60–75% in August and 80–85 % in December. In winter the precipitation is mainly snow, varying from 70–90% at the lower altitudes to 100% at higher. The average number of days with snow cover varies from 20–30 to 120–160. The highest thickness of the snow cover reaches 40–60 cm at 1000–1800 m in February and 160–180 cm above 1800 m in March (190 cm on Vihren). In some winters the snow thickness can reach 250–350 cm. Avalanches are frequent.
  The prevailing wind direction is from the west and the north-west but southern and south-western winds are also frequent. The wind speed can reach 34–40 m/s at the high ridges, being highest in February and March and lowest in August and September. The percentage of windless days increases in summer and autumn to 30–40% at lower altitude and 10–15% at higher. In the highest zone the percentage does not exceed 5–7% annually.
caption: Low clouds in Pirin
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