Istanbul is Turkey's most populous city, and its cultural and economic center. It is located on the Bosphorus strait, and encompasses the natural harbor known as the Golden Horn (Turkish: Haliç), in the northwest of the country. Istanbul extends both on the European (Thrace) and on the Asian (Anatolia) side of the Bosphorus, and is thereby the only metropolis in the world which geographically is situated on two continents. Location Istanbul encloses the southern Bosphorus which divides it into a western, European and into an eastern, Asiatic area. The Golden Horn, a Bosphorus bay running to the west, separates the European part into a southern, between Marmara Sea and Golden Horn lying peninsula which is the historical Istanbul and the northern quarter to the historical Galata. Both to the west, to the north and the east Istanbul exceeds far over historical quarters. In the southeast the Prince's Islands belonging to Istanbul lie. The city boundaries cover a surface of 1.538,77 km². The Metropol region (= province Istanbul) has a surface of 5,220 km². Climate The city has hot and humid summers with cold, rainy and often snowy winters. Yearly precipitation for Istanbul averages 870 mm. Humidity is often rather high which can make temperatures feel much warmer or colder than they actually are. The average maximum temperature during the winter months varies between 7°C (46° F) and 10°C (51° F). Snowfall is common and can occasionally be heavy. It is most likely to occur between the months of December and March. The summer months of June through September bring average daytime temperatures of 28 °C (82 °F). The warmest month is July with on the average 23.2 degrees Celsius, coldest January with 5.4 degrees Celsius on the average. The highest recorded temperature in Istanbul is 40.5 °C (105 °F) (August 2000), with the lowest being –16.1 °C (3 °F) (February 1927). The weather becomes slightly cooler as one moves toward eastern Istanbul. The city is quite windy, having an average wind speed of 17 km/h (11 mph). Summer is by far the driest season, although there is no real summer drought such as occurs further west, and so the climate cannot be considered truly Mediterranean. Economy Istanbul has always been the centre of the country's economic life because of its location at an international junction of land and sea trade routes. The economy of Istanbul stands solidly on two columns: nationally it dominates trade and it also has international significance. Istanbul employs 20% of Turkey's industrial labour and contributes 38% of Turkey's industrial workspace. The city generates 55% of Turkey's trade and 45% of the country's wholesale trade, and Istanbul generates 21.2% of Turkey's gross national product. Istanbul contributes 40% of all taxes collected in Turkey and produces 27.5% of Turkey's national product.