Hijacking your question as I was born in and grew up in Cape Town. August will still be a bit cold unfortunately, as it's still winter, with possible rain, but there are usually a few gorgeous sunny days too, and, importantly, you won't be crowded with tourists. And the wind won't be bad - summer is the windy season.
Personally I'd go out of Cape Town to explore other parts of the Western Cape, like the Garden Route and the Klein (Little) Karoo, as it's safer than Cape Town itself. (The Garden Route is also much warmer in winter - I even swam in the sea one winter as the water was fine.)
But still, you'll be ok in Cape Town if you don't 'look like' a tourist - don't wear a backpack, keep valuables out of sight, and ignore any strange people who come up to you with a story or offers of help. We have a lot of good charitable organisations and NGOs that support homeless people, so the beggars on the street are usually scammers, you don't have to feel sorry for them or give them anything. Say no and walk ahead like you know where you're going.
I recommend visiting Simonstown - a little village and naval base. Boulders Beach is there and there are penguins who managed to get lost on the way to/from Antarctica and now have a colony there. They are protected and happy. Some lovely restaurants and coffee shops along the main road.
Next, the Kirstenbosch Botanical Gardens are magnificent - highly recommend. Don't go to the touristy restaurant at the bottom of the gardens - rather walk up the hill to the top entrance where there is a little coffee shop that does scones with cream and jam.
Travel inland to the winelands and visit Franschhoek - there are fine dining restaurants there, such as La Petite Colombe, which has been awarded three Michelin stars.
Visit Hout Bay for fresh fish and chips and take a drive/taxi along Chapman's Peak - the sea and mountain views are exquisite.
Enjoy :)