Going to be very hot and dry that time of year. I can never get used to the dry air in SA, it gives me nose bleeds and headaches! It gets cold really quick after sundown too so pack more warm clothes than you would think you might need.
My own view - dont choose your animals before you see them! There are so many species in SA hunting doesnt need to be very difficult unless you get fussy about what you want to shoot. FWIW I would take a black wildebeest over a blue or a hartebeest any day of the week (but if you want a black one I have a spare in my basement that I could be persuaded to part with).