May in Negombo is the rainiest and the cloudiest month of the year. In May, the weather in Negombo is typically hot. Average daily high temperature in May is about 29 degrees above zero. On average, Negombo has 30 rainy and 1 partly cloudy day in May. The rains are usually heavy. May as well as March, April, June, and July is considered the most uncomfortable time to visit Negombo.