April in Phonsavan is the warmest month of the year. In April, the weather in Phonsavan is typically warm. Average daily high temperature in April is about 26 degrees above zero. On average, Phonsavan has 23 rainy, 4 sunny, 2 cloudy, and 1 partly cloudy day in April. The rains are usually heavy. April as well as May, June, July, and August is considered the most uncomfortable time to visit Phonsavan.