its waters but most of the drinking water used in Skopje comes from a karstic spring in Rašče, west of the city. Geology The Skopje valley is bordered on the West by the Šar Mountains, on the South by the Jakupica range, on the East by hills belonging to the Osogovo range, and on the North by the Skopska Crna Gora. Mount Vodno, the highest point inside the city limits, is 1066 m high and is part of the Jakupica range. Although Skopje is built on the foot of Mount Vodno, the urban area is mostly flat. It comprises several minor hills, generally covered with woods and parks, such as Gazi Baba hill (325 m), Zajčev Rid (327 m), the foothills of Mount Vodno (the smallest are between 350 and 400 m high) and the promontory on which Skopje Fortress is built. The Skopje valley is near a seismic fault between the African and Eurasian tectonic plates and experiences regular seismic activity. This activity in enhanced by the porous structure of the subsoil. Large earthquakes occurred in Skopje in 518, 1555 and 1963. The Skopje valley belongs to the Vardar geotectonic region, the subsoil of which is formed of Neogene and Quaternary deposits. The substratum is made of Pliocene deposits including sandstone, marl and various conglomerates. It is covered by a first layer of Quaternary sands and silt, which is between 70 and 90 m deep. The layer is topped by a much smaller layer of clay, sand, silt and gravel, carried by the Vardar river. It is between 1.5 and 5.2 m deep. In some areas, the subsoil is karstic. It led to the formation of canyons, such as the Matka Canyon, which is surrounded by ten caves. They are between 20 and 176 m deep. Climate Skopje has a borderline humid subtropical climate (Cfa in the Köppen climate classification) and cold semi-arid climate (BSk). with a mean annual temperature of . Precipitation is relatively low due to the pronounced rain shadow of the Prokletije mountains to the northwest, being significantly less than what is received on the Adriatic Sea coast at the same latitude. The summers are long, hot and relatively dry with low humidity. Skopje's average July high is . On average Skopje sees 88 days above each year, and 10.2 days above every year. Winters are short, relatively cold and wet. Snowfalls are common in the