If you're looking for an escape to a sunny beach while in South Africa then the obvious answer is Durban. Enjoy this beach city where the nightlife and the beautiful beaches/marine activities will keep you busy all day long.
Durban feels like a sunny California coastal town, which makes a lot of sense as it's equidistant from the equator as San Diego. Take time to relax at the beach while here which is nearly a mile and a half long with various "beachy" activities along the way. It's the perfect way to enjoy the Indian Ocean.
Near town is where Crocodile Creek hosts thousands of reptilian nightmares to see in person. take a hike, see the waterfall, and enjoy the wild animals thriving in this area.
The world famous Garden Route is a 200km stretch of highway along the southern coast of South Africa linking Cape Town with Port Elizabeth. This route along is a must for any traveler, but the adventurous folks will extend that all the way to Durban for a combination of popular visited, beautiful coastline with back road local routes enjoying the charm of being off the beaten path.
Durban's winter is May - August and temperatures drop to a comfortable average high of 74F.
Summer in Durban is November - March when highs are in the mid-80's and people frequent the local beaches. Think of it like southern California.