We started the hike at around 6 am, and seeing how hot it was getting as we were coming down around noon, I was very glad that we got an early start. South Sister is definitely the most challenging in the Central Oregon Challenge, and the second two thirds are quite exposed, so sun screen and an early start are advisable. The challenge was an enjoyable one, and the reward of having accomplished getting the summit and enjoying the incredible Central Oregon views was well worth it, but it was the most challenging hike for me, with lots of steep and somewhat loose surfaces. I normally don't hike with trekking poles, but I found myself feeling very glad that I had borrowed a set, as they were very helpful and confidence boosting both going up and coming down.