Chile
Chile Geography & Climate
Geography
Chile is a strip between the Andes and the Pacific: about 4,300 kilometres north to south, averaging less than 180 kilometres across and never more than about 350. Almost every part of the country is within a couple of hours of both mountains and ocean.
The Atacama occupies the north — the driest non-polar desert on earth, with stations that have recorded no rainfall in the period they have been measured. Its dry, high, still air is why the world's astronomers build here. South of it, the Central Valley between the coastal range and the Andes holds most of the population, the farmland and the vineyards. Further south the land fragments into lakes and volcanoes, then into the fjords, glaciers and islands of the Patagonian south.
Chile sits directly on the boundary where the Nazca plate dives beneath South America, which makes it one of the most seismically active countries anywhere. The 1960 Valdivia earthquake measured magnitude 9.5 — the most powerful ever recorded, anywhere, and its tsunami killed people in Japan and Hawaii. The 2010 Maule quake reached 8.8. Building codes here are correspondingly serious, which is why a large quake does far less damage in Chile than the same quake elsewhere.
Roughly a tenth of the world's active volcanoes are Chilean. Offshore, Chile administers Rapa Nui and the Juan Fernández Islands, and claims a wedge of Antarctica.
A country of one dimension
Chile is around 4,300 kilometres long and averages under 180 wide, a shape produced by the Andes on one side and the Pacific on the other. It spans some 38 degrees of latitude — the equivalent of stretching from Norway to the Sahara — which is why the north is the driest desert on earth and the south is glacier and rainforest, with everything in between arranged in bands.
The subduction zone
The Nazca plate slides beneath South America off this coast at around eight centimetres a year, which builds the Andes, feeds a chain of active volcanoes and makes Chile the most seismically violent country on the planet. The 1960 Valdivia earthquake, at magnitude 9.5, remains the largest ever instrumentally recorded anywhere.
Climate Patterns
Because Chile spans 39 degrees of latitude, it contains almost every climate except the tropical. Seasons are southern-hemisphere: summer is December to February, winter June to August.
The north is desert — hot by day, cold at night, and at altitude around San Pedro the night-time swing is severe in any season. The Central Valley including Santiago is Mediterranean: hot dry summers, mild wet winters. Santiago sits in a basin ringed by mountains, and its winter smog can be bad.
The Lake District is temperate and genuinely rainy, with Valdivian rainforest to show for it. The Patagonian south is cool, wet in the west and dry in the east, and above all windy: the Torres del Paine wind in summer regularly exceeds 100 km/h.
Two things catch visitors out. UV levels are extreme in the north at altitude and in the far south under a thinned ozone layer — burns happen fast in both. And the coast is cold everywhere, because the Humboldt Current runs the length of the country; the Pacific here is not for swimming, even at the latitude of the Sahara.
The Humboldt current
Cold water flowing north along the coast cools the air above it, suppressing rain and producing the coastal fog the Chileans call camanchaca. It is the reason the Atacama is as dry as it is — some weather stations have never recorded rain — and the reason the central coast is cooler than its latitude suggests. It also supports one of the most productive fisheries in the world.
Bands rather than seasons
Because the country runs north to south, its climate varies more with where you are than with when you go. The far north is desert year round; the centre is Mediterranean, with hot dry summers from December to February; the lake district and Patagonia are cool, wet and windy, with rainfall in places exceeding four metres a year; and the far south is subpolar. Planning here means choosing a latitude as much as a month.