Besides for people with leaky houses, the problem with the first heavy rains of the season is that stormwater drains and tunnels often collect lots dry grass, leaves, branches, and other rubbish.
When the first heavy rains hit you often find water being forced out of blocked drains into streets - which in turn is both fun to race your car though, and dangerous if you don't notice the water and drive into a deep puddle unexpectedly.
We had a fair amount of rain in Cape Town yesterday and today. Also a fair number of car accidents - which is typical on rainy Cape days. It seems as though Winter truly has arrived!