Generally, South Africa's climate allows for a sunny holiday at any time of the year. However, your dress requirements may vary according to your particular destination, so rather be prepared!
It you intend spending a lot of time outdoors and definitely in summer, bring a hat for protection against the rather scorching sun. In the summer, lightweight cotton clothing is advised because daytime temperatures generally hover around 25-30 degrees Celsius.
For the brief period of January until Mid-March, temperatures sometimes reach 35 degrees. During this period, the nights might be just as hot. In the Cape, with its Mediterranean climate, there is no rain to cool down the air. You may or you may not want to bring a costume to swim in. There are a few topless and nude beaches in South Africa, but generally nudity is still frowned upon.
Further inland there is often an afternoon or evening thunderstorm. In fact, the rain may become quite heavy, so a raincoat is advisable. In the summer evenings, the heat usually lessens and only a light jacket is required.
In the winter months (May to October) the sun shines almost every day. Daytime temperatures hover around 17 to 22 degrees celsius. The evenings can get very cold. Temperatures have been known to plummet to below zero in Johannesburg, Gauteng.
Early morning and late afternoon temperatures are rather chilly too. Still, South Africa is not a country where firs are worn. Generally, on most sunny winter days, trousers and a jersey are all that you may require. In the Mediterranean stretch along the south-western Cape, winters are wet.
Because winter temperatures do not justify having Central Heating in buildings and homes, Europeans tourists might find the winters harsher than South Africans do. We have become accustomed to the cold around us and simply put on more layers if necessary.
Only in the last couple of years have some houses installed under floor heating. In Johannesburg sometimes during winter, and in the Cape in the afternoon a rather chilly wind blows, so bring some wind-proof clothing along.