Three systems of circulation occur in the Middle-West region: the system of disturbed currents of the West, represented by unstable events during the summer; system of disturbed currents of the North, represented by Convergence Intertropical (CIT), that produces rains in the summer, autumn and winter in the north of the region; and the system of disturbed currents of the South, represented by the polar fronts, invading the area in the winter with great frequency, producing rains of one to three days duration. In the north and south extremes of the region, the annual medium temperature is 22 °C (71.6 °F) and in the Chapadas it varies from 20 to 22 °C (68 to 71.6 °F). In the spring and summer, temperatures are commonly high, the average of the hottest month varying from 24 to 26 °C (75.2 to 78.8 °F). The average of the maximum temperatures of September (hotter month) oscillates between 30 and 36 °C (86 and 96.8 °F).
The people of the westwinter is an interesting season, low temperatures occurring quite frequently. This is caused by the polar invasion, that produces the cold weather which is very common at this time of the year. The medium temperature of the coldest month oscillates between 15 and 24 °C (59 and 75.2 °F), and the average of the minimum temperatures ranges from 8 to 18 °C (46.4 to 64.4 °F). Minimum temperatures are sometimes negative.
The characterization of the pluviosity of the region is almost exclusively due to the system of atmospheric circulation. The annual medium pluviosity varies from 2,000 to 3,000 mm (78.7 to 118.1 in) in the north of Mato Grosso, to 1,250 mm (49.2 in) in the Pantanal mato-grossense.
In spite of this inequality, the region is well provided with rain. Its seasonality is typically tropical, with maximum in the summer and minimum in the winter. More than 70% of the total rain that is accumulated during the year falls from November to March. The winter is excessively dry, because the rains are very rare.