June in Dumai is the sunniest and the hottest month of the year. In June, the weather in Dumai is typically hot. Average daily high temperature in June is about 31 degrees above zero. On average, Dumai has 24 rainy, 5 sunny, and 1 cloudy day in June. The rains are usually heavy. June as well as January, February, March, and April is considered the most uncomfortable time to visit Dumai.