It is sad that all these rivers are very polluted. You an not swim in them. We learned at our talk at the Centre for Conservation Education that the rainfall in Cape Town is about the same very year. Some years it is earlier in the season and other times it is later. We get our rain mostly in winter.
Cold fronts bring in the rain.
Sometimes it rains for days and days without because of the mountain chain. The one side is much wetter that the other side, so different plants cover the slopes. The rest of the country gets its rain in summer. Sometimes it hails, The biggest hailstorm had pieces of hail the size of golfballs and this was in 1983. Often it rains so much that roads are flooded and trees fall over.