May in Saint-Germain-en-Laye is the rainiest month of the year. In May, the weather in Saint-Germain-en-Laye is typically warm. Average daily high temperature in May is about 17 degrees above zero. On average, Saint-Germain-en-Laye has 19 rainy, 6 sunny, 3 cloudy, and 3 partly cloudy days in May. The rains are usually moderate. May as well as January, February, March, and November is considered the most uncomfortable time to visit Saint-Germain-en-Laye.