The winters are generally mild, comparing favourably with European summers. But we do get some days when temperatures sky-dive, especially in high-lying areas such as the Drakensberg, so be prepared with jerseys and jackets. If you are going to the Cape, rain gear will be needed in this season.
For the summers, bring clothes that are cool and comfortable, along with an umbrella or rain jacket, as this is when most of the country gets rain. A light jacket or wrap is a good precaution. Don't forget a swimming costume.