In this region, 22 million people live. Its geographic localization places in the position north – eastern of the country between 1 and 1830' of south latitude and 3420' 4830' of longitude West of Greenwich. Forming the half-barren northeastern who satisfies about 60% northeast Brazilian. Possessed person a Half-barren Climate that is predominant in the region of the hinterland and the valley of the river San Francisco, also located in the Northeast region. He is characterized by raised average temperatures, of about 27C, with annual variations around 5. Through a derivation the tropical climate that occurs in the hinterland northeastern, where the annual precipitations badly reach 600 mm, provoking existence of a vast semidesert-like area of almost a million of Km2. The irregularity of precipitations, caused for the presence or not of the Continental Equatorial mass in the south of the Region or the displacement of the intertropical front in the north, causes the phenomenon of the great droughts, that bring serious consequences for the Northeast and its population. In Cabaceiras, in the Paraba, it presents only 278.1 mm of annual rains.
Rains beyond scarce are very irregular, having great variation in the pluviomtrico regimen: thus, the rain regimen with maximum in the autumn, characterizes the Cear, the Rio Grande of the North, the Paraba and Pernambuco, whereas in the Bahia predominates summer rains. They are some methodologies that elucidate this mark of dry on the Brazilian northeast. Had to chapadas and the plateaus of the wasteland northeastern that are organized parallel to the eastern coast, hindering the humidity and rains that could arrive through east chains (Tropical Atlantic and Equatorial Atlantic). Already in the northern coast, the temperature of the level of the sea is more cold (to the south of the equator), weakening the possibility of advance of the humidity of air. In this way, the estiagem sufficiently is delayed (between eight and ten months) and confronted for the strong pluviomtrica abnormality, that in determined moments, as those affected by the El Nio in the South Oscillation, can last of three the four years.