I went the end of July 2012
Advice is do not think it will be hot
Their winter has an average tempreture like our mild summers (18 degrees)
But the evenings can be really cold in some of the areas that you go to.
You will see that the locals wear wooly hats, but that's because they are not used to the milder weather.
When I toured Cape Town, they were wrapped up and I had jeans, shirt and Jacket
http://www.youtube.com/playlist?list=PLEDC1E9007DE14F37