Northeast
Northeast Geography & Climate
Geography
The northeast lies between two great rivers and is the wettest, greenest part of Argentina.
The rivers
The Parana and the Uruguay enclose the region and eventually join to form the Rio de la Plata. Both are enormous, and the Parana is the second-longest river in South America after the Amazon. Their floodplains and the land between them are the Mesopotamia argentina.
Iguazu
The falls sit where the Iguazu river meets the edge of an ancient basalt flow and drops off it in a horseshoe roughly 2.7 kilometres across, divided by rocky islands into around 275 separate falls. The Devil’s Throat takes about half the flow into a narrow chasm eighty metres deep. Average flow is around 1,500 cubic metres a second and has exceeded ten times that in flood.
Misiones and the red earth
The province is a wedge of rolling hills on deep lateritic red soil, coloured by iron oxide, carrying the southern remnant of the Atlantic Forest — a rainforest distinct from the Amazon and far more depleted, of which this is one of the largest surviving fragments.
The Ibera wetlands
Around 13,000 square kilometres of marsh, lagoon and floating islands in Corrientes, fed entirely by rainfall rather than by a river, and among the largest wetlands on the continent.
Why Ibera is unusual
Most great wetlands are fed by a river. Ibera is not — it sits in a shallow depression left by an old course of the Parana and is filled almost entirely by rainfall, which makes its water exceptionally clear and low in sediment. Floating islands of matted vegetation, some large enough to carry trees, drift across the lagoons and are what the capybara and caiman lie on.
Chaco Province
West across the Parana, a hot, flat, thorny dry forest that is one of South America’s least visited landscapes.
Climate Patterns
The northeast is the wettest and most humid part of Argentina, with a subtropical climate and no dry season at all.
Rainfall
Misiones receives around 1,800 to 2,000 millimetres a year, spread through every month, which is what sustains the Atlantic Forest. There is no reliable dry window, and a week here will usually include rain whenever you come.
Summer
December to February is hot and very humid, with highs of 33 to 38°C and overnight lows barely below 24. Afternoon thunderstorms are frequent and violent. Walking the Iguazu catwalks in January is genuinely hard work, and the heat rather than the rain is what spoils visits.
Winter
June to August is mild and pleasant, 18 to 24°C by day, with occasional cold snaps when polar air pushes north — it can drop close to freezing for a night or two, which surprises people.
The falls and the flow
Iguazu’s volume depends on rain in the Brazilian catchment upstream rather than locally. After heavy rain the falls are overwhelming and the lower walkways and boat trips close; in drought the flow can reduce dramatically, and in 2006 and 2020 it nearly stopped. Neither is forecastable far ahead.
The forest depends on it
The Atlantic Forest exists because rain falls in every month. Unlike the Amazon it has no dry season to survive, and the plants and animals are adapted to constant moisture, which is part of why the fragments left are so biologically rich and so vulnerable. Clearing changes the local rainfall as well as removing the trees, which is the argument conservationists in Misiones make most often.
Humidity
High year round, and the reason the region feels hotter than the thermometer says.