Long wetsuits needed all year round - although people were seen in shorties some times. Air around 30°C in the summer, down to 15°C in the winter. The water is pretty cold, around 10-15°C in the summer and 13-17°C in the winter. The longer the South Easter (prevailing summer wind) blows, the colder the surface water gets. Doesn't matter much in summer though.
Scarborough is a small village on the Cape Peninsula. Drive towards Kommetjie and keep going further south, following signs until you reach Scarborough. In the Scarborough turn left towards the beach, it is the only road going down to the beach here. You can park at the end of the road.