August in Lanzhou is the rainiest month of the year. In August, the weather in Lanzhou is typically warm. Average daily high temperature in August is about 23 degrees above zero. On average, Lanzhou has 15 rainy, 8 sunny, 7 partly cloudy, and 1 cloudy day in August. The rains are usually heavy. August as well as February, March, September, and November is considered the most uncomfortable time to visit Lanzhou.