I am living in South Africa in Mpumalanga and would rather consider April before August. August is normally very windy, therefore if you plan to shoot plains ( Blesbuck/ Springbuck) you will have a very good chance of shooting in 20 m/h ( 30km/h ) winds at 250+ M. April is normally warm with day tempretures reaching high 20's deg C.
If you planning any Bushveld hunts you have an increased chance of snakes in the veld in April.
To get the most out of a trip rather aim for June / July.
My 2C......enjoy your trip, make the most out of your trip and go to Kruger Park (Lowveld), Table mountain in Cape Town and try to Hunt the plains and bushveld.
Nice places ( Combination of Mix) where you can hunt is Pongola Game reserve (Natal Bushveld) and Rhino Lodge( Highveld plains). Both places offer great service....I am taking my 7 year old on her first hunt to Pongla in June.
Enjoy your trip...