April in Phnom Penh is the hottest month of the year. In April, the weather in Phnom Penh is typically hot. Average daily high temperature in April is about 36 degrees above zero. On average, Phnom Penh has 15 rainy, 8 sunny, and 7 partly cloudy 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 Phnom Penh.