December in Umuarama is the rainiest and the hottest month of the year. In December, the weather in Umuarama is typically hot. Average daily high temperature in December is about 29 degrees above zero. On average, Umuarama has 25 rainy and 6 sunny days in December. The rains are usually heavy. December as well as January and February is considered the most uncomfortable time to visit Umuarama.