As someone who grew up in South Africa I can confirm it. I grew up in the north of the country where in winter it can dip to just below freezing during the night and early morning. It would be back up to 16 degrees at lunchtime though.

I now live in the U.K. and although house quality and insulation is appalling compared to other places it is still infinitely warmer here in the middle of winter than in South Africa.

Coldest I have ever been was going back to visit family during winter there. My wife, who is from Germany and used to -5 to -10 in winter, would take a lot of persuading to visit South Africa in the middle of winter again.