August in Grenoble is the sunniest month of the year. In August, the weather in Grenoble is typically warm. Average daily high temperature in August is about 21 degrees above zero. On average, Grenoble has 24 sunny, 4 rainy, and 3 partly cloudy days in August. The rains are usually moderate. August as well as {{month_nom: February}}, and {{month_nom: February}} is considered the most comfortable time to visit Grenoble.