January in Porto Velho is the rainiest, the cloudiest, and the coldest month of the year. In January, the weather in Porto Velho is typically warm. Average daily high temperature in January is about 27 degrees above zero. On average, Porto Velho 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 Porto Velho.