What is the best time to hike Great Wall of China?

Dear all, I am planning to travel China this year and my first trip will be The Great Wall. We would like to hike the Great   Wall with a guide. Could anyone of you tell me when is the best time to hike Great  Wall? Is it very hot in September?

Thanks in advance!

Hello Joice, happy to help you then. Great Wall of China is very famous in the world. Foreign visitors who come to China must have a look at it. It is ok for you to hike Great Wall in September. It is not so hot in September in Beijing and the North of China.It is  also ok to visit Great wall in October and November. If  your time is enough, you can also visit it in Aprial, May.

I hiked the great wall in Oct and the whether was just fine, a little bit hot during the day (30 Centigrade, I think), but it was cold when I was sleeping on the wall during the night, my sleeping bag was not warm enough..... I hiked from Gubeikou to Jinshanling for the first day and continue the hike to Mutianyu, I loved it very much.
I like this hiking package on the great wall for 2 days in Jinshanling and Simatai, these section of the great wall is the origional part of the wall from Ming Dynasty, unlike the Great Wall in Badaling, which was rebuild lately.
Please copy the link below and check whether you will like it or not. http://www.chinahighlights.com/tour/beijingtour/bj-7/

Picture of the wall

This is a 5 days hiiking tour: http://www.chinahighlights.com/tour/beijingtour/bj-6/