Does it rain more in Johannesburg or Sun City?

Expected rainfall in Johannesburg is same as in Sun City. You can expect this to be the case over the next 18 days.

Is Johannesburg weather warmer or cooler than Sun City?

You can imagine temperatures to be in the 31 °C range in January. The weather in Sun City is generally hotter than Johannesburg's. As flight availability is subject to become more limited as peak season approaches it is ideal to book in a timely manner.