San Carlos de Bariloche - Climate and Geography

Climate and Geography

Bariloche has a cool Mediterranean climate (Köppen Csb) with dry, windy summers and rainy winters, which grades to an alpine subpolar oceanic climate at higher altitudes. Generally speaking, the summer season (mid-December to early March) is characterized by long stretches of windy, sunny weather, with pleasant afternoons of 18 to 26 °C (64 to 79 °F) and cold nights of 2 to 9 °C (36 to 48 °F). Autumn brings colder temperatures in March, then stormier weather in April and May. By mid-May the first snows fall, and winter lasts until early September, bringing stormy weather with mixed precipitation (snow, rain, sleet), occasional snowstorms and highs between 0 and 12 °C (32 and 54 °F), lows between −12 and 4 °C (10 and 39 °F). Spring is very windy and variable; temperatures may reach 25 °C (77 °F) in October and then plummet to −6 °C (21 °F) following a late-season snowfall. On average, there are a handful of snowy days between 5 and 15 centimetres (2 and 6 in) every year, and many more days with mixed precipitation. However, there have been extreme snow events in the past that have brought well over a foot of snow (30 cm) to the entire city, and well over a meter in some higher areas.

Within the city limits, several geographic features have an impact on the weather, creating several micro-climates. Generally, the city follows, for over 15 km from east to west, the shores of Nahuel Huapi lake, which is over 10 km wide in front of the city centre and extends over more than 70 km to the northwest, toward Villa La Angostura. West of the city, the fjord known as Brazo Blest extends for another 50 km, and these two features allow strong westerly and northwesterly winds to reach the city. Most central areas and almost all tourist areas are located along the shoreline; they are thus "sandiwched" between higher elevations on the south and the extensive lake at 765 meters above sea level on the north. This position, on a north-facing slope next to open water, creates a moderate micro-climate: during the summer, daytime temperatures very rarely reach over 30 °C, staying most often in the 18 °C to 25 °C range, with nights usually between 2 and 9 °C (36 and 48 °F). During the winter, most days reach between 3 and 9 °C (37 and 48 °F), whilst nights are often between −5 and 4 °C (23 and 39 °F), depending mostly on cloud cover. Snowfall is usually light, and although snow depth can often reach 0.1 metres (4 in) after a snowstorm, it will usually not last more than two or three days. Extreme low temperatures rarely fall below −10 °C (14 °F), although −15 °C (5 °F) may be reached on occasion. The main feature of this area is the strong, westerly winds that sometimes reach over 100 km/h, especially between September and December. Precipitation ranges from over 1,800 millimetres (70 in) at the western end of the city (Llao Llao) to only 600 millimetres (24 in) at the eastern end (Airport).

Right behind the city centre, the area known as "El Alto" forms a plateau at about 900 m of altitude. Being far away from the lake and at a higher altitude, the weather tends to be more extreme, especially in the winter: it is not uncommon to see sleet storms hit the downtown area while El Alto is covered in snow. It is also not unusual to have more extended periods of snow cover (up to one or two weeks at a time), with depths sometimes exceeding 0.2 metres (8 in), and temperatures of −10 °C (14 °F) are frequent. On occasion, temperatures below −18 °C (−0 °F) will also be recorded.

The slopes of Cerro Otto (1405 meters above sea level), right west of the city centre, often have deep snow cover: cross-country skiing and dog sledding can be practiced for a few months every year. The neighbourhood of Villa Catedral, at about 990 meters above sea level, sees colder temperatures and increased snowfall: on the coldest winters, this hub, which serves as the base of a ski resort, can be snow covered through the winter, sometimes with over 50 cm snow (in 2007, accumulations reached 100 cm!). However, on most winters, this condition is only met above 1200 meters, where most of the slopes of the resort are located.

Higher elevations see much colder conditions: the top of Cerro Catedral, 30 km from the city centre, sees snow cover from late April till at least December, with a maximum in early September that usually reaches well over 150 cm (in 2007, over 400 cm were recorded). The tree line is located between 1,600 m (southerly slope) and 1,800 m (northerly slope), and snowstorms happen in the summer as well.

Water temperatures at the Nahuel Huapi lake vary from a high of 14 °C in late summer and a low of 7 °C in early spring. Alpine streams and ponds often have much lower temperatures, and can be frozen for months.