South America

South America runs from north of the Equator to the subantarctic latitudes of Cape Horn, with most of its landmass in the tropics. The Andes — the longest continental mountain system on Earth — split the continent climatically: tropical lowlands of the Amazon, the Orinoco, and the Brazilian Highlands sit east of the chain, while a narrow Pacific margin to the west swings from rainforest in Colombia's Chocó to the hyper-arid Atacama and on to the cold Patagonian steppe. Within the Andes themselves, equatorial latitudes still reach permafrost and glaciers because of altitude.

The seasonal rhythm is set by the Intertropical Convergence Zone, which migrates north and south across the continent, and a strong monsoon flow that drenches the Amazon basin and central Brazil through austral summer. Off the Pacific coast, the Andes and the coastal range cast a two-sided rain shadow that the cold Humboldt Current reinforces, leaving the Atacama the driest non-polar desert on Earth at a long-term mean of about 15 mm of rain per year, while the same cold water produces the camanchaca coastal fog.

In the south, near-constant westerlies and the Andes rain shadow leave Patagonia cold and dry, with annual mean temperatures around 3°C. The continent is also strongly affected by El Niño and La Niña, which reshuffle rainfall and ocean productivity from Ecuador to Argentina.

Our archive covers 5 South American cities with daily ERA5 reanalysis data going back to 1940. The warmest July averages occur in Rio de Janeiro, around 24.1°C, while Bogotá records the coldest January nights near 8.6°C. Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 0.8°C.