Weather, Maps and some AI

Brazil's best climates sit on the Planalto Atlântico, the spine of plateaus that runs behind the coast from Rio Grande do Norte to Paraná. I scored every INMET weather station with a published climate average, 216 in all, on three simple rules. Summer afternoons between 23°C and 28°C, winter nights above 5°C, and less than 900 mm of rain a year. Inside that spine, 7 in 10 stations score good or better. Across the rest of Brazil, 3 in 10. Only 7 stations come out near perfect, and 5 of them sit on the spine. The best is Morro do Chapéu, a small town 1,002 meters up in Bahia's Chapada Diamantina. Its hottest afternoons average 28°C, its coldest nights 15°C, and it gets just 626 mm of rain a year. Vitória da Conquista, 923 meters up in the same state, is second. Garanhuns in Pernambuco, Itamarandiba and Diamantina in Minas Gerais round out the five. Air cools about 6.5°C for every 1,000 meters you go up. That one rule gives these tropical plateaus spring-like weather. Of the 33 stations above 800 meters, 28 score very good or better. Of the 58 stations below 100 meters, 4 do. Curitiba scores highest of all the capitals, with July nights near 9°C at 924 meters up. Brasília makes the very good tier too, with its hottest month averaging 29°C at 1,161 meters. Drive west to Cuiabá, almost the same distance from the equator but only 151 meters up, and the hottest month averages 34°C. The extra height explains most of that gap. Ten capitals score harsh, and every one sits in the north or center-west, from Manaus and Belém to Palmas and Cuiabá. Rain is the one thing that holds the highlands back, since most of them get around 1,500 mm a year. The other two near-perfect spots are the exception to the altitude rule. Rio Grande and Santa Vitória do Palmar, on the Rio Grande do Sul coast near Uruguay, score near perfect at sea level because their summers top out at 28°C. Brazil's best weather runs along the highlands behind the beaches everyone pictures.