August in Gangtok is the rainiest month of the year. In August, the weather in Gangtok is typically warm. Average daily high temperature in August is about 21 degrees above zero. On average, Gangtok has 22 rainy, 7 cloudy, 1 sunny, and 1 partly cloudy day in August. The rains are usually heavy. August as well as July is considered the most uncomfortable time to visit Gangtok.