Autumn in China is by far the best time to be here. The temperatures throughout the country are milder without the extremes you can experience in winter and summer, and without the wetness you'll experience in the spring. While the days are getting shorter, you can still have warmish daytime weather in November in the north and central parts of China and in the south, you'll find it can still be quite warm.
Depending on where you are, you can see some leaves changing color. Gingko trees are especially beautiful in the fall. The leaves turn bright gold and can turn a sidewalk into a veritable Yellow Brick Road.
The most glorious thing about being in China in the fall is that you'll find you can spend a great deal of time out of doors and be very comfortable. It's an ideal time for sight seeing on the Great Wall as you'll likely get to see some fall colors. It's a great time to do any kind of hiking since you'll find it rather dry. And, outside of the October Holiday (for National Day on October 1 - see below), fall sees fewer travelers so attractions won't be as crowded as they are in the summer when schools are out.
Fall Holidays in China
Early Autumn sees quite a few big holidays in China. The Mid-Autumn Festival is a tribute to fall itself, celebrating the full harvest moon with mooncakes and a day off. October 1st is China's National Day garnering a big public holiday and usually 3-5 days off for workers and school children.
China's National Day
China begins its week-long national celebration every October 1st.
Celebrating American Thanksgiving
And in case you were wondering, here's the scoop on celebrating Thanksgiving (Americans. Sorry Canadians, the Chinese ignore yours.) in China.
Viewing Fall Foliage: If you're coming to China to see the fall colors then the best thing you can do is head out of the big cities and into nature. While it's understandably hard to imagine natural scenery when you're sitting in a Beijing traffic jam, only an hour outside the city is the Great Wall, a fantastic place to see fall colors. Famous places for viewing beautiful fall scenery include the Great Wall.
Sichuan Province: Jiuzhaigou Nature Reserve is one of the most glorious places to see fall foliage. The reserve itself is a beautiful natural park with mountain lakes and vivid colors.
Anhui Province: Yellow Mountain nature area is famous for its scenery year-round but fall grants unique views as the leaves covering the mountains change colors.
Xinjiang Autonomous Region: there are a large number of scenic spots in Xinjiang that offer beautiful autumn colors including the Kanas Nature Reserve.
Enjoying the Outdoors
If you can schedule part of your trip to take you out of the major cities and into the countryside, then autumn is a fantastic time to do it. But you don't necessarily have to travel all over the country to get in some nice outdoor activities. There are plenty of day trips and side-trips from big cities like Beijing and Shanghai that offer outdoor adventure. In fact, ensure you spend plenty of time at parks and doing walking tours in the cities you're visiting and you'll be taking advantage of the glorious fall weather.