The climatic characterization of the Northeast area is a little complex, and the four systems of circulation that influence the region are denominated Systems of Disturbed Currents of South, North, East and West. The System of disturbed currents of South is represented by the polar masses that reach the area in the spring-summer, acts in the coastal areas until the south of Bahia, bringing frontal and back-frontals rains. In the winter the polar masses reach even the coast of Pernambuco, while the hinterlands regions remain under the influence of the tropical mass.
The system of disturbed currents of North, represented by Convergence Intertropical (CIT), produces rain from the summer to the autumn even in Pernambuco, in the vicinity of the Raso da Catarina. On the other hand, the currents of the East are more frequent in the winter and they usually produce abundant rains in the coastal regions, rarely reaching the scarps of the Plateau of Borborema (800 m/2,625 ft) and of Chapada Diamantina (1,200 m/3,937 ft).
Finally, the system of currents of the West, brought by the lines of Tropical Instability (IT), occur from the end of spring to the beginning of autumn, rarely reaching the states of Piauí and Maranhão.
Temperatures are high, with annual averages between 20 and 28 °C (68 and 82.4 °F), maximums of around 40 °C (104 °F) having been observed in the south of Maranhão and Piauí. The months of winter, mainly June and July, produce minimum temperatures between 12 and 16 °C (53.6 and 60.8 °F) in the coastal regions, much lower in the plateau regions where temperatures of 1 °C (33.8 °F) have been recorded in Chapada Diamantina after the passage of a polar front.
The pluviosity of the area is complex and is source of concern: its annual totals vary from 2,000 mm (78.7 in) to values even lower than 500 mm (19.7 in), as verified in the Raso da Catarina, between Bahia and Pernambuco, and in the depression of Patos in Paraíba. In a general way, the annual medium precipitation in the northeast area is lower than 1,000 mm (39.4 in) - in the city of Cabaceiras, interior of Paraíba, was observed the smallest annual pluviometric index registered in Brazil, 278 mm (10.9 in)/year. Besides it in the interior of this area the rainy period is usually of just two months in the year, sometimes not coming in some years, causing then the denominated regional droughts.