Patagonia
Patagonia Geography & Climate
Geography
Argentine Patagonia covers roughly 800,000 square kilometres south of the Colorado River, and it divides sharply into two.
The steppe
Most of it is a dry, windswept plateau of gravel and tussock grass stepping down eastward to the Atlantic, with almost no trees and very few people. This is the Patagonia of the travel writers: horizon, wind and space, crossed by Route 40 running two thousand kilometres along the foot of the Andes.
The Andes and the ice
Along the western edge the mountains carry the Southern Patagonian Ice Field — at around 13,000 square kilometres, the largest mass of ice outside the poles and Greenland, shared with Chile. From it descend some fifty major glaciers, including Perito Moreno, which is unusual in being roughly in balance rather than retreating, and which periodically dams an arm of Lago Argentino until the water breaks through in a spectacular rupture.
The peaks
Fitz Roy and Cerro Torre are granite towers rather than snow peaks, among the hardest technical climbs in the world, and they make their own weather.
The Atlantic coast
Cliffs, gravel beaches and sheltered gulfs. Peninsula Valdes is a UNESCO site for its marine mammals, and its Valdes Depression is the lowest point in South America at 42 metres below sea level.
Petrified forests and dinosaurs
The steppe is one of the richest fossil landscapes on earth. Patagonian beds have produced Argentinosaurus and Patagotitan, among the largest animals ever to walk, along with giant carnivores and the dinosaur egg fields of Auca Mahuevo. At Jaramillo, a petrified forest of Jurassic conifers lies scattered across the gravel as stone trunks up to three metres thick.
Tierra del Fuego
The island at the far south, shared with Chile, where the Andes turn east and the Beagle Channel cuts through.
Climate Patterns
Patagonia’s climate is defined by the wind, which is relentless and shapes everything from the vegetation to the way people build.
The westerlies
The Roaring Forties and Fifties blow across this latitude with almost nothing to stop them, and Patagonia takes them full on. Summer winds of 60 to 100 km/h are routine on the steppe and in El Chalten, where they can knock a walker off balance; trees on the exposed steppe grow permanently bent. The wind is strongest in summer, which is counterintuitive and catches out trekkers who planned for January.
The rain shadow
The Andes wring the moisture out of the westerlies on the Chilean side. The result is stark: temperate rainforest a few kilometres west of the divide, and arid steppe receiving under 200 millimetres a year immediately east of it. The transition can happen within a single valley.
Temperature
Cool rather than cold. Summer averages 13 to 20°C, winter around 0 to 7°C in most of the region, with Ushuaia colder and the steppe subject to hard frosts. The far south has extremely long summer days and correspondingly short winter ones.
Four seasons in a day
A genuine cliche here. Weather in the mountains changes within the hour, and Fitz Roy is clouded on most days of the year — seeing it clear is a matter of luck and patience.
Planning around the wind
The practical advice most visitors are not given is to treat wind rather than rain as the forecast that matters. El Chalten’s walks are perfectly manageable in drizzle and genuinely hard in a 90 km/h westerly, and the shoulder months of November and March are calmer as well as quieter. Anyone kayaking, cycling or climbing should build spare days in for being wind-bound.
Ultraviolet
Very high, from thin ozone and reflection off ice.