May in Sihanoukville is the cloudiest month of the year. In May, the weather in Sihanoukville is typically hot. Average daily high temperature in May is about 29 degrees above zero. On average, Sihanoukville has 29 rainy and 2 partly cloudy days in May. The rains are usually heavy. May as well as April, June, July, and August is considered the most uncomfortable time to visit Sihanoukville.