April in Siem Reap is the hottest month of the year. In April, the weather in Siem Reap is typically hot. Average daily high temperature in April is about 33 degrees above zero. On average, Siem Reap has 28 rainy and 2 sunny days in April. The rains are usually heavy. April as well as May, June, July, and August is considered the most uncomfortable time to visit Siem Reap.