Gauteng is said to offer one of the world's best climates: summer days are warm and wind free and winter days are crisp and clear. Johannesburg and Pretoria differ in temperature by about 2%, last being the warmer.
Johannesburg has a delightfully mild climate, neither humid nor too hot for comfort. There are about six weeks of chill in mid-winter (from July to August). Summer, offering warm African sunshine followed by balmy nights, runs from October to March.
The seasons are flexible, one running into the next, and summer habitually spills over into spring and autumn. The nights can be chilly particularly in winter. Bring a jacket to wear in the evenings. The rainy season is in summer rather than winter. Rainstorms are often harsh accompanied by much thunder and lightning and occasional hail, but they are brief and followed by warm sunshine.
Pretoria's climate is similar to that of Johannesburg, but it lies at a somewhat
lower altitude than its neighbor and its air temperatures are, on average, about two degrees higher. This is a summer-rainfall region. Between November and February summer thunderstorms produce flashes of lightning and brief but torrential afternoon downpours. Summer days are hot, though rarely to the point of discomfort.
KwaZulu Natal Climate:
Visitor to KwaZulu Natal can look forward to a splendid climate. The largest city, Durban enjoys warmth and sunshine very occasionally mixed with light, steady rainfall. In
Durban the air is heavy with humidity and the subtropical latitude of the city brings with it long, hot summers with rainfall, and very mild winters.
Durban boasts an average of 320 days of sunshine a year. Temperatures range from 16 to 25? C in winter and from 23 to 33? C during the summer months between September and April. January is generally Durban's hottest month, with an average daily temperature of +/- 32?C. The warm Mozambique current flowing along the coast means wonderfully warm bathing throughout the year, the water seldom falling below 17? C even in the middle of winter. With these conditions, it's no accident that Durban is considered the "holiday city" of KwaZulu Natal.Further north, conditions become subtropical to an even greater extent, and the estuarine environment of St Lucia and Kosi Bay brings steamy days and balmy nights.
Moving inland, the low-lying coastline makes way for the emerald hills of Zululand and Thukela
regions, and still further east to the Great Escarpment, as altitudes rise and temperatures drop. The chilly towns of Bergville and Winterton provide a refreshing break from the swelter.