The climatic conditions of the Brazilian plateau are widely different from those of the coast in many respects. There is less uniformity in temperature, and the elevated _chapadas_ are generally hotter during the day and cooler at night than are localities of the same latitude on the coast. The Brazilian Guiana plateau, lying immediately north of the equator, is in great part a hot, stony desert. Geographically it belongs to the Amazon basin, as its western and southern slopes are drained by tributaries of that great river. Climatically, however, it is a region apart. It lies in the north-east trade winds belt, but the mountain chain on its northern frontier robs these winds of their moisture and leaves the greater part of the Brazilian plateau rainless. Its eastern and western extremities, however, receive more rain, the former being well forested, while the latter is covered with grassy _campos_. South of the Amazon valley and filling a great part of the eastern projection of the continent, is another arid, semi-barren plateau, lying within the south-east trade winds belt, and extending from Piauhy southward to southern Bahia. It covers the state of Piauhy and the western or inland parts of the states of Ceará, Rio Grande do Norte, Parahyba, Pernambuco and Bahia. The year is divided into a dry and wet season, the first from June to December, when rain rarely falls, the streams dry up and the _campos_ are burned bare, and the second from January to May when the rains are sometimes heavy and the _campos_ are covered with luxuriant verdure. The rains are neither regular nor certain, however, and sometimes fail for a succession of years, causing destructive _sêccas_ (droughts). The interior districts of Ceará, Pernambuco and Bahia have suffered severely from these _sêccas_. The sun temperature is high on these barren tablelands, but the nights are cool and refreshing. The prevailing winds are the south-east trades, which have lost some of their moisture in rising from the coastal plain. In summer, becoming warmed by the heated surface of the plateau, they sweep across it without a cloud or drop of rain. In winter the plateau is less heated, and cold currents of air from the west and south-west cause precipitation over a part if not all of this region. South and south-west of this arid plateau lie the inhabited tablelands of Rio de Janeiro, São Paulo and Minas Geraes, where the climate is greatly modified by a luxuriant vegetation and southerly winds, as well as by the elevation. Minas Geraes is forested along its water courses and along its southern border only; its sun temperature, therefore, is high and the rainfall in its northern districts is comparatively light. São Paulo is partly covered by open _campos_, and these also serve to augment the maximum temperature. In both of these states, however, the nights are cool, and the mean annual temperature ranges from 68° to 77°, the northern districts of Minas Geraes being much warmer than the southern. In São Paulo and southern Minas Geraes there are sometimes frosts. In the Parahyba valley, which extends across the state of Rio de Janeiro, the mean temperature is somewhat higher than it is in São Paulo and Minas Geraes, and the nights are warmer, but the higher valleys of the Serra do Mar enjoy a delightfully temperate climate. The rainfall throughout this region is abundant, except in northern Minas Geraes, where the climatic conditions are influenced to some extent by the arid eastern plateau. South of São Paulo the tablelands of Paraná, Santa Catharina and Rio Grande do Sul enjoy a temperate climate, with an abundant rainfall. There are occasional frosts, but snow is never seen. Of Goyaz and Matto Grosso very little can be said. The lower river valleys of the Tocantins-Araguaya, Xingú, Tapajós and Paraguay are essentially tropical, their climate being hot and humid like that of the Amazon. The higher valleys of the Paraná and its tributaries, and of the rivers which flow northward, are sub-tropical in character, having high sun temperatures and cool nights. Above these, the _chapadas_ lie open to the sun and wind and have a cool, bracing atmosphere even where high sun temperatures prevail. The mean annual temperature at Goyaz (city), according to a limited number of observations, is about 77°. There is no absolutely dry season in this part of the great Brazilian plateau, though the year is customarily divided into a dry and wet season, the latter running from September to April in Goyaz, and from November to April in Matto Grosso. The prevailing winds are from the north-west in this region, and westerly winds in the rainy season are usually accompanied by rain.