December in Cuiabá is the rainiest and the cloudiest month of the year. In December, the weather in Cuiabá is typically hot. Average daily high temperature in December is about 29 degrees above zero. On average, Cuiabá has 30 rainy and 1 sunny day in December. The rains are usually heavy. December as well as January, February, March, and April is considered the most uncomfortable time to visit Cuiabá.