Turku is a city on the southwest coast of Finland at the mouth of the Aura River, in the region of Southwest Finland. Turku, as a town, was settled during the 13th century and founded most likely at the end of the 13th century, making it the oldest city in Finland. It quickly became the most important city in Finland, a status it retained for hundreds of years. After Finland became part of the Russian Empire (1809) and the capital of the Grand Duchy of Finland was moved to Helsinki (1812), Turku continued to be the most populous city in Finland until the end of the 1840s, and it remains a regional capital and an important business and cultural center.
Because of its long history, it has been the site of many important events, and has extensively influenced Finnish history. Along with Tallinn, the capital city of Estonia, Turku was designated the European Capital of Culture for 2011. In 1996, it was declared the official Christmas City of Finland.
Due to its location, Turku is a notable commercial and passenger seaport with over three million passengers traveling through the Port of Turku each year to Stockholm and Mariehamn.
As of 31 December 2016, the population of Turku was 187,564, making it the sixth largest city in Finland. There were 318,168 inhabitants living in the Turku sub-region, ranking it as the third largest urban area in Finland after the Greater Helsinki area and Tampere sub-region. The city is officially bilingual as 5.2 percent of its population identify Swedish as a mother-tongue.
Located at the mouth of the Aura river in the southwestern corner of Finland, Turku covers an area of 245 square kilometres (95 sq mi) of land, spread over both banks of the river. The eastern side, where the Cathedral of Turku is located, is popularly referred to as täl pual jokke ("this side of the river"), while the western side is referred to as tois pual jokke ("the other side of the river"). The city center is located close to the river mouth, on both sides of the river, though development has recently been expanding westward.
There are ten bridges over the Aura river in Turku. The oldest of the current bridges is Auransilta, which was constructed in 1904. The newest bridge is Kirjastosilta ('library bridge'), a pedestrian-only bridge built in 2013. The Föri, a small ferry that transports pedestrians and bicycles across the river without payment, is a well known feature of the city.
With a population of approximately 300,000, the Turku Region (LAU 1) is the third largest urban region in Finland, after Greater Helsinki and the area around Tampere. The region includes, in addition to the city itself the following municipalities: Askainen, Kaarina, Lemu, Lieto, Masku, Merimasku, Mynämäki, Naantali, Nousiainen, Paimio, Piikkiö, Raisio, Rusko, Rymättylä, Sauvo, Vahto, and Velkua.
A more exclusive definition for the urban area is the city region of Turku with a population around 235,000 consisting of four major municipalities Kaarina, Raisio, Naantali, and Turku.
Situated by the Baltic Sea and sheltered by the islands of the Archipelago Sea, Turku has a humid continental climate (Köppen dfb). Like much of southern Finland, the city experiences warm summers, with temperatures ranging up to 30 °C (86 °F), and relatively cold winters with frequent snowfall. The warmest month of the year is July, with an average temperature of 17.5 °C (64 °F), whereas the coldest month is February. The average year-round temperature is 5.5 °C (42 °F). Winter usually starts in early December, and spring in late March.
Precipitation in Turku averages 720 mm (28.3 in) a year. The rainiest month of the year is August, when the city receives on average 80 mm (3.1 in) of rainfall. In April, the driest month of the year, the figure is only 32 mm (1.3 in). The average air pressure at sea level is 101.2 kilopascals (29.9 inHg), with little variance throughout the year.
Operational since 1955, the city's weather station is located at an altitude of 47 metres (154 feet) at Turku Airport.