Yunnan Weather in August

In short: favorable temperature, high precipitation
 In the daytime, with the average high temperature of about 25°C (77°F), the weather is mild and pleasant compared with many other China cities experiencing scorching hot summer; while at night, the weather is relatively cool with the average low temperature of around 15°C (59°F). In this region, August is one of their rainiest months, with an average precipitation of over 200 mm and about 20 rainy days. The climate is changeable, which cannot be forecasted accurately. You can still go out for a visit even on a day when the weather forecast says it’s going to rain because the rain usually stops quickly; just bring with you an umbrella. The UV rays are extremely strong on sunny days, especially at midday.

Stone Forest, Kunming

 With high altitudes, these places are still cool in August of summer, with the average temperature of 10 - 20°C (50 - 68°F). You should know that snowy mountains, such as Jade Dragon Snow Mountain, and other higher-altitude places may be a little cold. Rainfall is also at a high level in these places, with above 20 rainy days on average.
 Specifically, the temperature in the morning and at night is comfortable at about 20°C (68°F). Then, at noon hours, you may face relatively high temperatures of over 30°C (86°F) and high UV rays, which are not conducive for outdoor activities. August is the rainy season and the rain, although frequent, doesn’t last long. Even though, always bring rain gear. On the plus side, it will be cooler and the air will be fresher after the showers.