We were in SA in Sept. and the morning drives were very cold indeed. Long underwear, thick socks, leather gloves, wool hat, windproof fleece lined jacket, scarf, hot water bottle and blanket. We are from CA, but still. In an open moving vehicle it is cold

A very few blossoms were appearing on the leafless trees. Bulbs coming out in Johannesburg.

Of course I can't speak to whether it will be warm on the particular days you're on safari; I've been in the Kruger area in July - middle of winter - when it was in the high 80s during the day, and I've been there in late September when it was cloudy and chilly (never cold, but people have different standards.) Like shouldbewriting says, the morning game drives in September in the Kruger area can be quite chilly, but - usually - by the late morning it's warmed up enough for short sleeves, and often some time in the pool. For what it's worth, if it's super chilly, the safari vehicles all have blankets.

The big difference, and the reason I'd choose September, is that the winter is the dry season in the north of the country. That means a couple of things: first, there's less foliage blocking your views; as things leaf out, the animals can vanish into the "thicket" much more quickly than earlier. Second, there are few to no mosquitoes, so no need for malaria prophylaxis, which some people find unpleasant and expensive. And third, because it's the dry season, the animals come to the water holes and small reservoirs, often right on the various lodge properties. Not only can you see a good variety of wildlife on game drives by hanging out near the water, but sometimes, depending on the lodge, you can see a lot right from your room. Here's the view from the door of our rondavel/cottage on the Chitwa Chitwa property in the Sabi Sand reserve:



By October I'd imagine the wildflowers in the Western Cape will be in decline, maybe gone, but the weather in Cape Town will probably be improving. Its general climate is more like San Francisco's than Seattle's, but I've also been there in mid-August when there were people on the beaches (and on other days when it was raining and rather bleak.) In general we've had excellent weather in September, but of course no guarantees. Note that the Indian Ocean is quite a lot warmer than the Atlantic, so if your plans included the Garden Route, or places like Addo, you'll find the weather along the Indian Ocean coast considerably warmer than in Cape Town. (By the time you get as far north as Durban, you're getting close to subtropical conditions.)

So I'd say September, and as I said, start in the north and work south, so that as you travel you're chasing the good weather. Just my view.

@Gardyloo...Many thanks for your insight. I didn’t even think about the mosquitoes or lack of foliage...certainly important points to consider. Looks like we will be traveling in September. We have looked at the Panaorama Route you suggested. OMG!!! What gorgeous scenery! That is high on our list.