Game viewing is exceptional in the Kruger from August
Johannesburg and the highveld is mild to cool by day, cold at night, and dry. Cape Town and the Western Cape is warm by day, cool at night, and receives regular rainfall.
The Kruger Park and surrounds is hot by day, cool at night, and dry.
August is an ideal time for beach holidays on the Indian Ocean coastline of KwaZulu-Natal coast, which tends to be temperate to hot over the nominal winter months, and very dry. Conditions on the coast of the Eastern and Western Cape are less predictable.
Game viewing in the Kruger Park and other reserves tends to be exceptional towards the end of the dry season, as animals congregate close to perennial water sources and the undergrowth clears to improve visibility.
August usually heralds the start of whale-viewing season in Hermanus and the Western Cape.
Accommodation in tourist areas is usually very quiet in August.
Taking everything into account, August is one of the best months to visit South Africa, particularly if your main interest is safaris rather than beaches.