May in Ferney-Voltaire is the rainiest month of the year. In May, the weather in Ferney-Voltaire is typically warm. Average daily high temperature in May is about 16 degrees above zero. On average, Ferney-Voltaire has 19 rainy, 6 partly cloudy, 5 sunny, and 1 cloudy day in May. The rains are usually heavy. May as well as January, February, March, and April is considered the most uncomfortable time to visit Ferney-Voltaire.