January in Rio Branco is the rainiest, the cloudiest, and the coldest month of the year. In January, the weather in Rio Branco is typically warm. Average daily high temperature in January is about 27 degrees above zero. On average, Rio Branco has 31 rainy days in January. The rains are usually heavy. January as well as February, March, April, and May is considered the most uncomfortable time to visit Rio Branco.