May in Laval is the rainiest month of the year. In May, the weather in Laval is typically warm. Average daily high temperature in May is about 16 degrees above zero. On average, Laval has 18 rainy, 7 sunny, 3 cloudy, and 3 partly cloudy days in May. The rains are usually heavy. May as well as March, April, June, and October is considered the most uncomfortable time to visit Laval.