May in Kalutara is the rainiest and the cloudiest month of the year. In May, the weather in Kalutara is typically hot. Average daily high temperature in May is about 28 degrees above zero. On average, Kalutara has 30 rainy and 1 sunny 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 Kalutara.