Buenos Aires

Buenos Aires is the capital and largest city of Argentina, and the second-largest metropolitan area in South America, after São Paulo. It is located on the western shore of the estuary of the Río de la Plata, on the southeastern coast of the South American continent. Greater Buenos Aires conurbation, which also includes several Buenos Aires Province districts, constitutes the third-largest conurbation in Latin America, with a population of around thirteen million.

The city of Buenos Aires is not a part of Buenos Aires Province, nor is it the Province's capital, but an autonomous district. In 1880, after decades of political infighting, Buenos Aires was federalised and removed from Buenos Aires Province. The city limits were enlarged to include the towns of Belgrano and Flores (both are currently neighborhoods of the city). The 1994 constitutional amendment granted the city autonomy, hence its formal name: Ciudad Autónoma de Buenos Aires (Autonomous City of Buenos Aires). Its citizens first elected a Chief of Government (i.e. Mayor) in 1996; before, the Mayor was directly appointed by the President of the Republic

People from Buenos Aires are referred to as porteños (people of the port). Buenos Aires is a top tourist destination, and is known for its European style architecture and rich cultural life. Buenos Aires is currently bidding to host the 2018 Summer Youth Olympics.

The limits of Buenos Aires proper are determined in the eastern part and north-east by the Rio de la Plata, in the southern part and southeast by the Riachuelo and to the northwest, west and Southwest by Avenida General Paz, a 24 km (15 mi) long highway that separates the province of Buenos Aires from the 203 km2 that form the city.

The city of Buenos Aires lies in the pampa region, except for some zones like the Buenos Aires Ecological Reserve, the Boca Juniors (football) Club "sports city", Jorge Newbery Airport, the Puerto Madero neighborhood and the main port itself; these were all built on reclaimed land along the coasts of the Rio de la Plata (the world's widest river).

The region was formerly crossed by different creeks and lagoons, some of which were refilled and others tubed. Among the most important creeks are Maldonado, Vega, Medrano, Cildañez and White. In 1908 many creeks were channelled and rectified, as floods were damaging the city's infrastructure. Starting in 1919, most creeks were enclosed. Notably, the Maldonado was tubed in 1954, and currently runs below Juan B. Justo Avenue.

Buenos Aires has a humid subtropical climate,climate zone characterized by hot, humid summers and cool winters, (Köppen Cfa), with four distinct seasons and an annual mean temperature of 17.7 °C (63.9 °F). The warmest month is January, with a daily average of 25.1 °C (77.2 °F). Most days see temperatures in the 28 to 31 °C (82 to 88 °F) with nights between 16 to 21 °C (61 to 70 °F). Heat waves from Brazil can push temperatures above 35 °C (95 °F), yet the city is subject to cold fronts that bring short periods of pleasant weather and crisp nights. Relative humidity is moderately high (64–70%) in the summer, so the heat index is higher than the true air temperature. The highest temperature ever recorded was 43.3 °C (110 °F) on 29 January 1957. Spring (September to November) and autumn (March to May) are generally mild and volatile, with averages temperatures of around 17 °C (63 °F) and frequent thunderstorms, especially during the spring.

Winters are temperate, though suburban areas often experience frost from May to September, as opposed to downtown Buenos Aires, which experiences the phenomenon only several times per season. Relative humidity averages in the upper 70s%, which means the city is noted for its moderate to heavy fogs during autumn and winter. July is the coolest month, with an average temperature of 10.9 °C (51.6 °F). Cold spells originating from Antarctica occur almost every year, and combined with the high wintertime humidity, conditions in winter may feel much cooler than the measured temperature. Most days peak reach 12 to 17 °C (54 to 63 °F) and drop to 3 to 8 °C (37 to 46 °F) at night. Southerly winds may keep temperatures below 10 °C (50 °F) for a few days, whereas northerly winds may bring temperatures above 20 °C (68 °F) for a few days; these variations are normal. The lowest temperature ever recorded in central Buenos Aires (Buenos Aires Central Observatory) was -5.4 °C (22 °F) on 9 July 1918. The last snowfall occurred on 9 July 2007 when, during the coldest winter in Argentina in almost thirty years, severe snowfalls and blizzards hit the country. It was the first major snowfall in the city in 89 years). On 17 July 2010, in the midst of another cold winter, snowfalls struck the southern reaches of Buenos Aires, but not the central parts as occurred in 2007 or 1918.

Spring is very windy and variable: there may be heat waves with temperatures of 35 °C (95 °F) even in early October, as well as periods of much colder weather with highs close to 10 °C (50 °F). Frost has been recorded as late as early November, although this is unusual. Severe thunderstorms are likely between September and December.

The city receives 1,242.6 mm (49 in) of rainfall per year. Rain can be expected at any time of year and hailstorms are not unusual.